LIBRARY 

OF  THE 

UNIVERSITY  OF  CALIFORNIA. 


\ 
Class 


SCIENCE  OF 
THRESHING 


Treating  the  Operation, 
Management  and  Care 
of  Threshing  Machinery 


BY     G.    F.CONNER 

\\ 


REVISED  EDITION 


PUBLISHED  BY 

The  Threshermen's  Review  Company 
ST.  JOSEPH,  MICHIGAN 


Copyright  1906 

The  Threshermen's  Review  Company 
All  Rights  Reserved       • 


PREFACE. 


In  no  other  line  of  industry  has  the  present  genera- 
tion witnessed  so  marked  a  degree  of  development 
as  in  the  design  and  manufacture  of  grain  handling 
machinery.  When  we  consider  the  difficulties  to  be 
encountered  and  the  obstacles  to  be  overcome  in 
taking  heads  of  grain,  husking  the  minute  kernels 
from  the  covering,  afterwards  known  as  chaff,  in 
which  Nature  has  enveloped  them,  depositing  the 
golden  grain  in  the  sack,  and  delivering  the  refuse 
according  to  the  will  of  the  operator  in  so  perfect  and 
expeditious  a  manner,  we  may  look  upon  the  modern 
thresher  as  a  marvel  of  success. 

To  the  thresherman  in  the  field  belongs  more  credit 
for  this  achievement  than  is  generally  accorded  him. 
He  is  the  final  dictator.  On  his  judgment  a  device 
must  stand  or  fall.  His  is  the  part  to  suggest,  the 
manufacturer's  to  execute.  And  even  now,  face  to 
face  with  the  proficiency  already  attained,  we  find 
that  there  is  room  for  more  and  deeper  study. 
Further  progress  can  be  made  by  all  working  in 
unison. 

By  some  the  position  is  taken  that  there  can  be 
formulated  no  definite  rule  by  which  to  operate  a 
machine,  and  this  is  true  to  a  certain  extent.  The 
same  may  be  said  with  equal  truthfulness  of  any  work 
requiring  skill,  as  skill  can  be  had  only  by  experience. 
Each  and  every  part  of  a  threshing  outfit,  from  the 
foot  board  of  an  engine  to  the  tail  end  of  the  straw 

192654 


carrier,  works  under  and  obeys  some  law  peculiar  to 
itself.  Unless  both  manufacturer  and  operator  under- 
stand the  various  laws  and  principles  which  govern  a 
device,  it  is  liable  to  fail  to  perform  the  functions 
intended,  though  both  parties  may  have  had  unlimited 
experience.  This  necessary  understanding  or  knowl- 
edge can  be  gained  much  more  easily  and  successfully 
than  by  depending  upon  the  slow  process  of  the 
school  of  experience  to  educate  and  teach  what 
should  have  been  understood  at  the  beginning.  As 
the  mind  will  grasp  information  from  any  source 
within  reach,  the  written  rule  is  much  the  better 
method  by  which  to  gain  a  knowledge  of  the  laws 
and  principles.  The  mind  must  first  be  informed  and 
then  the  hands  made  skillful.  Recognizing  this,  the 
author  has  endeavored  to  place  before  the  reader 
such  an  exposition  of  the  subject  under  consideration 
as  will  best  enable  him  to  reap  the  best  results  from 
his  labor. 

If  this  book  is  the  means  of  aiding  anyone  in  his 
part  of  the  work,  the  author  will  feel  conscious  of 
being  well  repaid  for  the  labor  and  time  consumed 
in  preparing  it. 

Due  acknowledgement  is  hereby  extended  to  all 
who  have  aided  in  any  way  to  make  it  a  success. 

GEORGE  F.  CONNER. 


Table  of  Contents. 

PART  I. 
CHAPTER  I. 

THRESHING.  9 

CHAPTER  II. 

THE    SEPARATOR. 

The  Threshing  Members — Cylinder,  Cylinder 
Teeth,  Concave,  Grate,  Feed  Board 14 

CHAPTER  III. 

THE  THRESHING  MEMBERS. 

Beater,  Check  Board.  The  Separating  De- 
vices— The  Rack,  Raddles,  Combination  of 
Rack  and  Raddle 23 

CHAPTER  IV. 

THE  GRAIN  CLEANING  MEMBERS. 
Sieves,  Fan,  Blast,  Sieve  Motion 32 

CHAPTER  V. 

THE  DELIVERY  MEMBERS. 
Stackers,  Weighers,  Measures,  etc 40 

CHAPTER  VI. 

FEEDING. 
Uniform,  Irregular,  Self  Feeders 43 

CHAPTER  VII. 

OPERATION. 

Weather  and  Grain  Conditions,  Cracking  Grain, 
Various  Kinds  of  Grain 47 


CHAPTER  VIII. 

THE    BLAST. 

Relation    to    Shoe,    Effect,     Proper    Strength, 
Sieves    55 

CHAPTER  IX. 

BELTS. 
Care  and  Management,  Adjustment,  Lacing.  ...    64 

CHAPTER  X. 

BABBITTING  BOXES. 
Babbitt  Metal,  Directions 68 

CHAPTER  XL 

LUBRICATION. 

Selection   of  Lubricants,    Cylinder  Oils,    Hard 
Oils,  Getting  Ready 70 

CHAPTER  XII. 

THE  CREW. 

Manager's  Duty,  Feeders,  Band  Cutters,  Pitch- 
ers,   Straw   Crew 74 

CHAPTER  XIII. 

WASTING  GRAIN. 

Losses  Easily  Overestimated,  No  Waste  Impos- 
sible, Reasonable  Waste 78 

PART  II. 

TRACTION  AND  PORTABLE  ENGINES. 
CHAPTER  I. 

HEAT. 

General  Theory,  Generation  of  Steam,  Temper- 
ature      83 


CHAPTER  II. 

LATENT   HEAT. 
Definition,  Energy,  British  Thermal  Unit 87 

CHAPTER  III. 

COMBUSTION  OF   COAL. 

Chemical  Combustion,  Distillation,  Fuel  Values, 
Evaporative   Power,    Heat   Conducting   Power     91 

CHAPTER  IV. 

PROPERTIES  OF  STEAM.  95 

CHAPTER  V. 

SATURATED  STEAM  AND  ITS  PROPERTIES. 

Heat  of  Liquid,  Latent  Heat,  Total  Heat,  Spe- 
cific Volume,  Density,  Steam  Tables 96 

CHAPTER  VI. 

THE    BOILER. 

Locomotive,  Return  Flue,  Vertical 103 

CHAPTER  VII. 

BOILER    FEEDERS. 

Atmospheric  Pressure,  Pumps,  Injectors 106 

CHAPTER  VIII. 

BOILER    PARTS. 

Fusible  Plug,  Grate,  Safety  Valve,  Steam  Gauge   1 1 1 
CHAPTER  IX. 

CARE  OF  THE  BOILER. 

Examination,  Steaming  Up,  Cleanliness,  Foam- 
ing     114 

CHAPTER  X. 

FIRING. 
Regularity,  Fire  Depth,  Ash  Pit 1 18 


CHAPTER  XL 

THE  MECHANISM  OF  THE  STEAM  ENGINE. 
Cylinder,    Eccentric,    Slide    Valve,    Governor, 
Speed  Changer 121 

CHAPTER  XII. 

SETTING  THE  VALVE. 

With  Remarks  on  the  Traction  Gear  and  the 
Traction  or  Drive  Wheels 134 

CHAPTER  XIII. 

WHISTLE   SIGNALS. 
Some  Poor  Practice,  Proper  Code 138 

CHAPTER  XIV. 

OPERATING  AND  HANDLING  OF  THE  ENGINE. 
Starting,  On  the  Road,  Guiding,  The  Friction 
Clutch,  Gear  Lock,  Setting.  .  . 141 

CHAPTER  XV. 

TESTS  FOR  LEAKS.  147 

CHAPTER  XVI. 

FRICTION  AND  LUBRICATION.  150 

CHAPTER  XVII. 

WINTER  CARE  OF  THE  ENGINE.       153 

CHAPTER  XVIII. 

SEPARATOR  AND  ENGINE  DONT's.  154 

CHAPTER  XIX. 

A  SUGGESTION.  157 


Science  of  Threshing. 


CHAPTER  I. 

THRESHING 

Threshing  is  the  process  of  removing  the  kernel  or 
grain  or  seed  from  the  stalk  to  which  it  is  attached. 
The  ordinary  threshing  machine  of  to-day  is  able  to 
operate  successfully  on  wheat,  rye,  oats,  barley,  rice, 
flax,  timothy,  millet,  buckwheat  and  peas. 

These  plants  carry  the  grain  or  seed  in  a  head,  each 
kernel  being  surrounded  and  held  in  place  by  a 
covering  or  hull.  Threshing  is  the  removing  of  the 
kernels  uncrushed  or  unbroken  from  this  covering, 
free  from  dust,  dirt  and  other  parts  of  the  plant. 
These  parts,  when  removed,  form  the  so-called  chaff. 

Naturally,  the  first  step  in  the  process  of  threshing 
is  to  loosen  the  hard  kernel  from  the  head.  This  is 
most  easily  done  by  striking  the  head.  In  Biblical 
times,  even  now  in  the  far  East,  this  pounding  or 
striking  was  done  by  spreading  the  unthreshed  grain 


10 


SCIENCE    OF   THRESHING. 


upon  a  prepared  threshing  floor  and  driving  horses 
or  cattle  over  it,  the  hoof  as  it  came  down  upon  the 
head  splitting  open  the  hull,  or  seed  pod,  and  forcing 
out  the  kernel. 


Later  this  result  was  accomplished  by  the  flail, 
which  is  nothing  more  or  less  than  a  mallet  having  a 
long  handle  which  enables  the  user  to  stand  fairly 
erect,  the  loosely  hung  long  head  of  the  mallet 
striking  a  quick,  sharp,  rebounding  blow,  which 
produces  a  jarring  shock  and  causes  the  kernels  to 
fly  out. 

With  the  present  plan  of  threshing,  the  grain  is 


SCIENCE    OF   THRESHING.  II 

struck  in  a  manner  similar  to  the  flail,  by  the  rapidly 
moving  teeth  of  the  cylinder  as  it  revolves.  The 
action  of  the  flail  is  increased  many  times  by  the 
increased  number  of  teeth  and  the  greater  speed  at 
which  they  travel.  Stationary  teeth  in  the  concave 
retard  and  hold  the  grain  in  place  while  being  acted 
on  by  the  cylinder  teeth.  The  "concave"  teeth  are 


arranged  so  the  cylinder  teeth  can  pass  between  them. 
The  unthreshed  grain  heads  are  laid  on  the  teeth  of 
the  concave,  and  the  cylinder  teeth  strike  them  quick, 
sharp  blows.  The  tendency  of  the  heads  to  bound 
back  from  the  teeth  forces  the  kernels  out  from  the 
hulls,  already  split  by  the  contact  with  the  teeth. 
Thus  it  is  seen  that  the  cylinder,  with  its  teeth, 


12 


SCIENCE    OF   THRESHING. 


and  the  concave  with  its  teeth,  are  the  parts  of  the 
modern  threshing  machine  which  perform  the  work 
of  the  horses'  hoof  of  ancient  days  and  the  flails  of 
more  recent  years. 

After  the  grain  had  been  stamped  or  beaten  out  on 
the  threshing  floor,  the  heavy  berries  were  separated 


from  the  straw  by  careful  raking,  and  from  the 
chaff  by  tossing  in  the  air,  the  wind  blowing  the 
lighter  refuse  away.  Or  else  air  was  forced  through 
the  grain — as  it  fell  in  a  thin  stream — by  a  fanning 
blanket.  Later,  the  fanning  mill  was  invented  to 
both  sift  and  blow  out  the  chaff. 


SCIENCE   OF   THRESHING.  13 

To-day  the  separator  performs  the  task  of  raking 
the  straw  and  sifting  and  fanning  the  grain.  In 
addition,  it  delivers  the  grain  in  one  place  and 
removes  the  straw  and  chaff  to  another.  It  performs 
these  widely  different  steps  by, 

First. — Loosening  the  kernels  from  the  heads. 

Second. — Separating  the  kernels  from  the  straw. 

Third. — Removing  the  chaff. 

Fourth. — Delivering  the  grain  and  straw  in  sepa- 
rate places. 


CHAPTER  II. 
THE  SEPARATOR 

While  varying  in  minor  details  the  modern 
thresher  consists  of— 

First. — The  threshing  members — the  cylinder  and 
concave,  with  their  teeth,  the  grate  and  the  feed 
board. 

Second. — The  separating  members,  which  separate 
the  loosened  grain  from  the  straw — the  beater, 
check-board,  racks  or  raddles. 

Third. — The  cleaning  members  which  remove  the 
chaff  and  dirt — the  cleaning  mill  or  shoe,  and  screens. 

Fourth. — The  delivery  members  which  carry  the 
grain  in  one  way  and  the  straw  in  another— the  grain 
spout,  tailings  elevator  and  straw  carrier. 

THE  THRESHING  MEMBERS 

CYLINDER. 

A  cylinder  consists  of  a  number  of  parallel  bars 

fastened  to  the  peri- 
pheries or  margins 
of  circular  discs, 
spiders,  or  heads  by 
means  of  bands 
shrunk  around  them, 
the  whole  being 

CYLINDER  mounted  on  a  suita- 

ble    shaft.      The 
14 


SCIENCE   OF   THRESHING.  15 

cylinder  teeth  are  inserted  in  sockets  in  the  bars,  and 
are  secured  by  nuts  on  the  inside,  or  by  wedges.  The 
cylinder  should  be  capable  of  endwise  adjustment  so 
that  its  teeth  may  be  made  to  run  centrally  between 
the  teeth  of  the  concave.  The  cylinder  acts  as  a 
balance  wheel  in  which  is  stored  power  to  maintain 
its  speed  when  an  undue  amount  of  straw  is  permitted 
to  enter.  There  are  usually  nine  or  twelve  bars  in 
the  cylinder. 

As  hitherto  indicated,  the  office  of  the  cylinder  is 
to  loosen  the  kernels  from  the  head.  This  is  accom- 
plished by  the  cylinder  tooth  striking  the  unthreshed 
head  with  sufficient  force  to  jar  the  kernels  loose  from 
their  retaining  hulls.  Therefore  the  cylinder  should 
run  with  sufficient  speed  to  entirely  free  all  the 
kernels  and  not  leave  any  on  the  straw.  If  for  any 
reason  the  cylinder  does  not  do  its  work  thoroughly, 
the  result  is  wasted  grain.  In  some  instances  some 
of  the  kernels  will  be  partially  loosened,  but  adhere 
to  the  head  until  nearly  through  the  machine,  when 
they  will  fall  out  and  be  carried  along  with  the  straw 
to  the  straw  stack,  thus  making  the  machine  appear 
to  be  at  fault  in  separation  by  wasting  the  grain, 
when  in  reality  the  threshing  members  are  not  doing 
their  work  properly.  The  usual  speed  of  ordinary 
cylinder  teeth  is  about  6,000  ft.  per  minute.  Under 
ordinary  circumstances,  this  will  thoroughly  dislodge 
the  kernels,  if  the  teeth  be  brought  in  contact  prop- 
erly with  the  heads.  In  dry,  brittle  grain,  a  slower 
speed  may  often  be  used  by  running  the  machine 


1 6  SCIENCE    OF   THRESHING. 

slower  which  will  thoroughly  dislodge  the  kernels 
and  not  break  the  straw  so  badly.  In  damp  and 
tough  grain  a  faster  speed  may  be  used  if  necessary 
to  thresh  the  straw  clear  of  kernels. 

On  account  of  the  cylinder  being  so  heavy  and  run- 
ning at  so  fast  a  speed,  it  should  be  kept  in  perfect 
balance,  as  it  greatly  adds  to  the  smooth  running  of 
the  machine.  When  the  cylinder  is  out  of  balance,  it 
is  easily  detected  by  the  jarring  or  vibrations  in  its 
vicinity.  By  placing  the  hand  upon  the  frame  work 
of  the  machine  near  the  cylinder  boxes  or  bearings,  a 
peculiar  jarring  may  be  plainly  felt  when  the  cylinder 
is  not  true.  The  side  on  which  this  is  most  evident 
will  indicate  the  end  of  the  cylinder  which  is  at  fault. 

If  permitted  to  run  out  of  balance,  the  cylinder 
will  have  a  tendency  to  cause  its  journals  to  heat  and 
wear  out  rapidly,  and  also  to  flatten  the  cylinder  shaft 
on  the  side  that  receives  the  wearing  strain.  A 
smoothly  running  cylinder  requires  a  minimum  of 
power  to  drive  it,  as  whatever  force  is  used  to  cause 
the  vibration  is  so  much  power  lost,  or  work  done  for 
nothing.  The  working  and  lasting  qualities  are  also 
lessened,  if  allowed  to  vibrate,  as  every  vibration  has 
a  tendency  to  loosen  the  framework  of  the  entire 
separator. 

A  cylinder  may  be  put  in  balance  by  removing  it 
and  placing  it  with  its  journals  resting  on  two  parallel 
straight  edges,  such  as  carpenters'  squares  set  up 
edgewise.  The  squares  or  straight  edges  should  first 
be  trued  up  with  a  spirit  level,  and  may  be  held  in 


SCIENCE    OF   THRESHING.  1 7 

i 

place  on  edge  by  driving  spikes  on  either  side  of 

them.  The  cylinder  will  adjust  itself  by  turning  on 
the  straight  edges,  the  heavier  side  going  down. 
Wedges  or  pieces  of  iron  of  the  right  weight  should 
be  driven  in  between  the  band  and  head  on  the  light 
side  of  the  cylinder  to  cause  it  to  balance  or  remain 
without  turning  in  any  position  in  which  it  may  be 
placed. 

If  cylinders  are  properly  balanced  when  they  come 
from  the  shop,  this  method  will  usually  put  them  in 
good  running  order.  However,  a  cylinder  may  seem 
to  be  in  good  balance  when  on  the  straight  edges, 
and  not  so  when  in  motion  in  the  machine,  the  cause 
being  that  one  end  is  heavy  on  one  side  while  the 
other  end  is  heavy  on  the  opposite  side.  In  such 
event,  the  cylinder  should  be  run  rapidly  in  loose 
boxes,  and  while  in  motion  a  piece  of  chalk  should 
be  held  steadily  near  enough  the  shaft  at  the  journal 
to  mark  it  slightly.  The  chalk  will  strike  and  mark 
the  heavy  side,  and  the  balancing  piece  should  be 
inserted  as  before,  both  ends  being  correspondingly 
trued. 

A  cylinder  is  sometimes  thrown  out  of  balance  by 
putting  in  some  new  teeth  irregularly  around  the 
cylinder,  leaving  part  of  the  old  ones  in.  In  this 
case,  the  remedy  is  to  replace  all  the  old  teeth,  when 
much  worn,  by  new  ones,  thereby  redistributing  the 
weight  in  an  even  manner. 

It  will  aid  the  cylinder  greatly  to  work  freely  and 
easily  if  the  separator  stands  still  on  its  trucks  while 
in  operation. 


I  8  SCIENCE    OF    THRESHING. 

CYLINDER  TEETH. 

The  cylinder  teeth  are  made  so  as  to  be  easily 
replaced  when  worn  out.  The  forward  side  of  each 
tooth  is  curved  slightly. 

If  perfectly  straight,  it  has  a  tendency  to  carry  the 
straw  into  the  machine  too  rapidly.  On  the  pther 
hand,  if  worn  too  much  it  retards  the  passage  of  the 
straw  into  the  machine,  thereby  interfering  with  the 
feeding.  The  cylinder  should  be  adjusted  so  the 
teeth  will  pass  midway  between  the  teeth  of  the 
concave.  If  permitted  to  have  too  much  side  play, 
or  to  run  too  close  to  the  concave  teeth,  the  teeth  will 
crack  the  grain  and  chop  the  straw  up,  and  at  the 
same  time,  will  permit  heads  of  grain  to  pass 
unthreshed  through  the  wide  openings  which  occur 
opposite  the  narrow  intervals.  The  teeth  sometimes 
become  loose  and  cause  delay.  This  is  especially 
true  of  new  teeth  when  first  inserted,  as  they  do  not 
always  fit  perfectly,  and  the  strain  to  which  they  are 
subjected  when  the  straw  becomes  compressed  in 
moving  through,  makes  them  move  a  little  in  the 
bars.  Accordingly,  new  teeth  should  be  watched 
carefully  when  first  inserted  and  tightened  up  until 
they  are  well  seated,  when  they  will  stay  in  place. 
Much  time  will  be  saved  by  going  over  the  cylinder 
each  day  and  tightening  up  the  new  teeth.  Many 
devices  have  been  used  to  keep  the  nuts  from  working 
loose,  some  of  which  have  considerable  merit. 
Wooden  bars  have  been  used  inside  of  the  cylinder, 
the  natural  spring  of  the  wood  permitting  the  teeth 


SCIENCE    OF   THRESHING.  19 

to  yield  a  little  without  becoming  loose.  A  twisted 
or  spiral  spring  bar  has  been  used  for  the  same  office. 
Teeth  do  not  loosen  so  badly  in  double  as  in  single 
bar  cylinders,  as  the  extra  length  of  shank  holds 
them  from  sidewise  movement  when  an  excessive 
amount  of  straw  is  encountered.  A  spring  steel 
split  washer  is  sometimes  used  under  the  nut  to  keep 
it  fast. 

It  is  needless  to  add  that  worn  teeth  retard  the 
proper  work  of  a  separator  and  should  be  replaced  by 
new  ones. 

THE  CONCAVE. 


The  concave,  so  called  because  of  its  dished  or 
hollow  shape,  consists  of  a  rack  or  grate  constructed 
to  conform  to  the  cylinder  under  which  it  is  adjust- 
ably hung.  It  is  provided  with  teeth  which  interact 
with  the  cylinder  teeth.  It  is  adjustable  to  and  from 
the  cylinder.  The  concave  holds  the  concave  teeth 
in  position  between  the  cylinder  teeth  and  forms  a 
floor  or  grate  over  which  the  straw  passes  while 
being  acted  upon  by  the  cylinder.  The  open  space 
between  the  teeth  permits  the  shelled  grain  to  fall 
through  as  soon  as  dislodged  from  the  heads,  thus 


2O  SCIENCE    OF   THRESHING. 

relieving  the  separating  devices  from  some  of  the 
work  of  removing  the  grain  from  the  straw.  Con- 
cave teeth  serve  the  further  purpose  of  retarding  the 
grain  while  it  is  being  acted  upon  by  the  cylinder 
teeth.  The  greater  the  number  of  teeth  the  more  the 
straw  will  be  retarded  and  acted  upon  by  the  cylinder. 
Separators  are  usually  constructed  to  use  concaves  of 
several  sections,  each  section  being  provided  with  two 
or  three  rows  of  teeth.  In  adjusting  the  position  of 
the  concave  relative  to  the  cylinder,  it  must  be  borne 
in  mind  that  some  grain  requires  very  positive  action 
on  the  part  of  the  cylinder  teeth  to  dislodge  the  grain 
from  the  head;  accordingly,  when  threshing  grain 
of  that  sort  it  is  well  to  set  the  concave  close  and 
employ  all  the  sections.  In  grain  that  is  less  stub- 
born, a  section  of  the  concave  may  be  removed  and 
replaced  by  one  without  teeth  with  good  results. 

There  should  be  stops  provided  to  prevent  the 
concave  from  being  raised  too  high  so  as  to  give  a 
proper  clearance.  It  is  better  practice  to  set  the 
concave  up  close  and  use  few  teeth  rather  than  to 
lower  the  concave  and  employ  a  greater  number. 
The  latter  plan  leaves  a  space  below  the  points  of  the 
cylinder  teeth  which  permits  the  straw  and  whole 
heads  to  pass  without  being  acted  upon.  If  the 
straw  be  very  dry  and  brittle  and  inclined  to  break  up 
badly,  it  lies  more  loosely  and  can  therefore  be  given 
a  considerable  more  space  by  letting  the  concave 
down. 

Some  types  of  concaves  are  adjustable,  both  at 


SCIENCE    OF   THRESHING.  21 

their  front  and  their  rear  edges.  The  proper  posi- 
tioning of  these  has  given  rise  to  much  discussion,  as 
some  experts  claim  that  a  cylinder  is  less  liable  to 
slug  when  the  front  edge  of  the  concave  is  the 
higher,  than  when  the  concave  is  fixed  in  the  opposite 
position,  as  the  wedge  shaped  opening  through  which 
the  straw  passes  broadens  as  the  straw  progresses  and 
does  not  tend  to  clog  or  bunch  it. 

THE  GRATE. 


A  grate  formed  of  slightly  separated  parallel  bars 
through  which  the  kernels  may  easily  fall  is  placed 
just  back  of  the  cylinder.  It  should  be  so  adjusted 
that  the  straw  in  passing  from  the  concave  will 
strike  it  at  an  angle ;  this  will  aid  the  separation  by 
affording  a  comparatively  straight  or  unobstructed 
path  for  the  -flying  kernels  which  are  thereby  less 
impeded  and  fall  through  more  readily.  This 
position  also  allows  the  passing  straw  to  sweep  the 
grate  cleanly,  and  to  prevent  it  loading  up  with  chaff 
and  sticks. 


22  SCIENCE    OF   THRESHING. 

THE  FEED  BOARD. 

The  feed  board  is  a  platform  placed  in  front  of  the 
concave  and  connects  with  it,  as  in  hand  feeding 
machines  on  which  the  sheaves  may  be  cut  and  spread 
for  presenting  to  the  cylinder.  The  surface  of  the 
feed  board  and  its  extensions,  or  tables,  should  be 
smooth,  and  free  from  nails  or  other  obstructions,  to 
facilitate  the  moving  of  the  straw. 

If  the  cylinder  does  not  have  sufficient  draft  or 
pull  to  take  the  straw  readily  enough,  the  edge  of  the 
feed  board  which  comes  in  contact  with  the  concave 
may  be  rounded  or  curved;  this  is  usually  a  good 
remedy.  A  desirable  point  in  the  working  of  a  sepa- 
rator is  also  gained  in  that  the  straw,  which  passes 
more  freely  over  this  rounded  edge  than  it  would 
over  an  abrupt  or  angular  margin,  is  not  broken  or 
cut  up  to  any  great  extent. 

It  is  good  practice  to  keep  the  lower  edge  of  the 
feed  board  on  top  of  the  concave  close  to  the  cylinder 
teeth,  even  when  the  concave  is  lowered,  thus  every 
head  is  acted  upon  by  the  cylinder  teeth  as  it  passes 
over  the  concave. 


CHAPTER  III. 

THE  SEPARATING  MEMBERS 

After  the  unthreshed  grain  is  passed  from  the 
feed  board  between  the  threshing  members,  the  cylin- 
der and  concave,  and  has  been  beaten  and  jarred  by 
their  interacting  teeth,  the  mingled  straw  and  loose 
kernels  of  grain  are  delivered  to  the  separating 
members. 


BEATER. 

In  its  most  common  form,  the  beater  consists  of  a 
shaft  carrying  two  circular  spiders  or  heads  between 
which  are  secured  beater  boards  or  wings  which 
extend  edgewise  from  the  center  shaft.  The  office  of 
the  beater  is  to  move  the  straw  away  from  the  cylin- 
der back  to  the  separating  parts.  Its  chief  usefulness 
is  in  preventing  the  straw  from  piling  up  back  of  the 
cylinder  where  it  is  liable  to  be  caught  and  wound  in 
between  the  cylinder  and  concave.  This  action  of 
the  machine  is  called  "back  lashing."  It  should  be 
so  placed  as  to  allow  the  grain  and  straw  to  strike  it 
as  they  come  from  the  cylinder  and  pass  either  over 

23 


24  SCIENCE    OF   THRESHING. 

or  under  it.  It  serves  as  a  check  to  the  flying  kernels 
from  the  cylinder.  However,  it  is  not  of  much 
benefit  as  a  separating  device  as  its  rapid  motion 
tends  to  carry  the  grain  along  and  throw  a  portion  of 
it  on  top  of  the  moving  straw.  Consequently,  it 
should  be  run  just  fast  enough  to  prevent  its  catching 
or  winding  damp  or  soft  straw,  its  position  being 
chosen  at  the  proper  distance  from  the  cylinder. 

Other  devices  are  used  instead  of  the  beater  to  pass 
the  straw  back  from  the  cylinder.  One  form 
resembling  somewhat  the  cylinder,  comprises  a  drum 
set  with  teeth.  Some  machines  work  very  well 
without  a  beater,  the  cylinder  delivering  the  straw 
directly  to  the  separating  device. 

THE   CHECK   BOARD. 

The  check  board  is  hung  directly  behind  the  beater 
to  arrest  flying  kernels.  It  is  a  sheet  iron  apron 
hinged  by  its  upper  edge  to  the  separator  frame, 
while  its  lower  edge  trails  on  the  top  of  the  stream  of 
moving  straw.  It  should  be  so  adjusted  as  to  prevent 
any  grain  passing  it  and  lodging  in  that  part  of  the 
straw  as  it  is  going  through  the  separator.  It  also 
acts  as  a  compressor  on  the  straw,  tending  to  reduce 
it  from  the  loose,  fluffy  condition  in  which  it  leaves 
the  beater  to  a  more  compact  layer. 

The  check  board  has  an  important  part  in  the 
proper  action  of  the  separating  devices,  and  its 
proper  adjustment  should  be  carefully  studied. 

THE  SEPARATING  DEVICES 
The  part  of  the  machine  which  is  of  equal  import- 


OF   THE 

UNIVERSITY 

SCIENCE  OF  THRESHING.  25 

ance  with  the  threshing  members  is  the  mechan- 
ism which  separates  (hence  the  name  "Separator") 
the  shelled  grain  from  the  straw  in  which  it  is 
entangled.  While  the  operation  seems  simple 
enough  on  first  thought,  there  are  some  things 
involved  which  render  the  devising  of  a  successful 
separator  very  difficult,  and  as  yet  no  one  has  con- 
structed a  machine  which  will  remove  every  kernel 
from  the  loose  straw  under  all  conditions  of  threshing. 
Gravitation  is  the  form  of  attraction  which  causes 
unsupported  bodies  to  fall.  Owing  to  inertia,  a 
falling  body  starts  to  fall  quite  slowly,  its  motion 
downward  increasing  in  a  fixed  ratio  as  it  continues 
to  fall.  A  body  placed  in  a  vacuum  will  fall  16  ft. 
the  first  second,  the  first  half  of  the  second  it  falls 
only  four  ft.  while  the  last  half  of  the  second,  owing 
to  its  increased  speed,  it  falls  12  ft.  It  requires  one- 
fourth  of  a  second  to  fall  the  first  foot.  The  sepa- 
rating of  the  grain  from  the  straw  is  done  by  gravity; 
time  must  be  given  the  kernels  to  fall  out  of  the 
straw.  In  falling  they  must  pass  down  through  the 
small  interstices  between  the  stalks. 

If  we  pick  up  a  quantity  of  straw  between  whose 
stalks  and  leaves  loose  kernels  of  grain  are  entangled, 
we  may  toss  the  bunch  or  bundle  around  up  and  down 
a  good  deal  without  dislodging  the  grain.  The 
kernels  will  remain  in  the  straw.  We  must  move  the 
stalks  of  the  bundles  about  among  themselves  in 
order  to  shake  the  kernels  out  from  their  resting 
places,  and  the  more  mildly  and  gently  we  do  this, 


26  SCIENCE    OF    THRESHING. 

within  certain  limits,  the  better  will  be  the  results. 

All  the  separating  devices  in  use  are  for  this 
purpose  of  thoroughly  agitating  the  straw  and 
thereby  allowing  the  kernels  to  fall.  This  causes  a 
limit  to  the  quantity  of  straw  which  any  machine  can 
handle,  as  time  must  be  given  for  the  dislodging  and 
falling  of  the  grain.  If  the  layer  of  straw  travels 
too  fast,  the  grain  is  carried  along  with  it.  If  it 
moves  too  slowly,  the  size  of  the  column  will  be 
correspondingly  increased.  If  the  straw  be  damp  and 
pliable,  it  will  form  a  more  compact  mass  than  if  dry 
and  elastic.  Some  kinds  of  grain  have  more  leaves 
than  other  kinds  and  these  mat  down  closely. 
Separation  is  retarded  by  these  conditions,  and  the 
feed  should  be  varied  in  speed  to  suit  them,  so  that 
the  straw  will  have  a  chance  to  open  up  and  allow  the 
grain  to  wrork  down  through  the  interstices  and  fall 
out  of  the  layer  onto  the  grain  rack  before  the  straw 
reaches  the  rear  of  the  machine.  The  intelligent 
thresher  will  bear  these  matters  in  mind  and  not 
crowd  his  machine  beyond  its  proper  capacity,  as  the 
result  will  be  unsatisfactory. 

However,  any  of  the  separating  devices  in  use  will 
handle  very  large  quantities  of  grain  and  straw  when 
operated  intelligently,  and  the  aim  should  be  to  gain 
the  best  results  in  both  quantity  and  quality  of  work 
done. 

Having  thus  noted  the  requirements  to  be  met  in 
adjusting  and  managing  the  separating  mechanism, 
the  different  types  can  be  intelligently  explained. 


SCIENCE    OF   THRESHING.  27 

The  separating  devices  in  use  may  be  divided  into 
three  general  classes:  first,  the  kinds  wherein  the 
straw  is  given  an  intermittent  or  step  by  step  move- 
ment through  the  machine  by  means  of  a  vibrating  or 
oscillating  rack  or  table;  second,  kinds  where  the 
straw  is  given  a  continuous  onward  movement  by 
traveling  raddles;  third,  where  the  straw  encounters 
a  combination  of  these  two  mechanisms. 

There  are  also  accessories  such  as  revolving  pickers, 
racks,  beaters  and  fingers  which  will  be  duly  consid- 
ered. 

THE  RACK. 

The  rack  or  table  usually  consists  of  a  series  of 
grates  or  parallel  slats  arranged  to  carry  the  straw, 
while  allowing  the  grain  to  fall  through. 


In  some  forms  of  racks  a  series  of  risers  are  placed 
on  the  surface,  which  have  lifting  fingers  which  are 
operated  by  a  lever  and  shaft;  they  tilt  backwords 
along  the  rack  and  are  given  an  up  and  down  motion 
as  the  rack  vibrates,  lifting  and  tossing  the  straw  as 
it  passes  over  them, 


28  SCIENCE    OF   THRESHING. 

Motion  is  imparted  to  the  racks  by  means  of  a 
crank.  In  some  instances  the  rack  is  hung  to  links 
so  that  the  crank  gives  it  a  swinging  motion  like  a 
pendulum,  as  is  shown  in  the  adjacent  cut,  its  path 
being  concave,  or  the  rack  may  be  supported  on  the 
upper  ends  of  rockers  in  which  case  it  oscillates  back 
and  forth  in  an  upwardly  curved  or  convex  path. 

The  rack  has  a  tendency  to  jar  and  compress  the 
straw  on  each  upward  stroke,  tossing  it  into  the  air 
very  slightly  and  moving  back  from  under  it.  The 
elasticity  of  the  straw  causes  the  mass  to  expand 
while  clear  of  the  rack.  As  it  falls,  it  meets  the  now 
ascending  rack  and  is  thus  given  another  sharp  com- 
pressing blow  which  tends  to  move  the  different 
straws  in  the  mass  upon  each  other.  The  most 
effective  blow  is  given  by  the  rack  at  the  middle  of 
the  stroke,  as  the  peculiarities  of  the  crank  motion 
cause  it  to  travel  fastest  at  about  this  point. 

It  is  plain  that  if  a  quantity  of  straw  and  grain 
should  lie  on  the  rack  and  vibrate  up  and  down  with 
the  rack,  and  not  move  away  from  it,  the  stalks 
would  maintain  their  relative  positions  and  not  give 
the  kernels  a  chance  to  fall  out.  To  be  effectively 
cleaned,  each  stalk  must  be  moved  as  related  to  its 
neighbor.  This  inter-motion  of  the  stalks  constitutes 
the  chief  feature  of  effective  separation. 

The  motion  of  the  rack  should  be  such  that  its 
upward  stroke  will  move  the  straw  onward  slightly, 
while  the  rack  is  permitted  to  descend  from  under  it. 
Gravity  will  then  start  the  straw  downward  with 
increasing  speed  as  it  approaches  the  rack.  The 


SCIENCE   OF   THRESHING.  29 

motion  thus  attained  will  cause  it  to  strike  the  rack 
with  a  sharp  jarring  motion  at  the  midway  point 
before  mentioned ;  if  the  rack  swing  has  been  properly 
timed  the  weight  of  the  falling  straw  will  add  to  the 
shock,  while  the  stiffness  of  each  straw  will  cause  it 
to  move  relatively  to  its  neighbor ;  as  soon  as  released 
at  the  up  end  of  the  stroke,  the  mass  will  expand  to  its 
normal  condition.  This  jarring,  compressing  and 
expanding  motion  accomplishes  the  desired  result  in  a 
remarkably  perfect  manner  when  the  layer  of  straw  is 
not  too  thick  or  bulky.  If  it  is  so  deep  that  the 
jarring  motion  is  not  felt  in  its  upper  part  the  result 
is  not  so  good.  The  upper  part  will  float  along 
undisturbed  because  of  the  elasticity  of  the  inter- 
vening straw;  if  the  rack  is  vibrated  so  as  to  throw 
the  straw  quite  high,  it  is  liable  to  toss  the  grain  too 
far  and  the  latter,  being  heavier,  will  go  higher  than 
the  straw  because  of  its  greater  momentum,  and 
retard  the  separation. 

Thus  the  straw  should  be  made  to  pass  over  the 
rack  in  a  layer  of  even  thickness  of  just  the  depth  to 
be  thoroughly  and  quietly  agitated  from  top  to 
bottom,  and  the  motion  of  the  rack  should  be  such  as 
to  strike  it  upward  blows  at  the  most  effective  point; 
that  is,  midway  of  the  upward  stroke. 

The  stroke  of  the  rack  is  usually  from  five  to  nine 
inches  in  length  and  the  number  per  minute  varies 
inversely  as  the  length,  the  long,  slow  stroke  passing 
as  much  straw  along  as  the  short  stroke  of  higher 
rate. 


30  SCIENCE    OF   THRESHING. 

The  manner  of  separation  is  seen  to  be  the  moving 
of  the  stalks  among  themselves  to  free  the  confined 
kernels  and  allowing  gravity  to  act  on  them,  causing 
them  to  fall  out.  The  speed  and  motion  that  moves 
the  stalks  among  themselves  with  the  least  upward 
motion  is  the  best  for  effective  separation. 

RADDLES. 

The  ordinary  raddle  is  constructed  of  parallel  belts 
running  over  pulleys,  connected  by  slats  which  are 
situated  far  enough  apart  to  permit  the  grain  to  fall 
through  while  carrying  the  straw  along.  If  their 
motion  is  quite  rapid  they  work  very  well,  as  the 
movement  keeps  the  sheet  of  traveling  straw  compar- 
atively thin,  thus  giving  the  kernels  opportunity  to 
fall  through.  The  raddles  should  be  of  sufficient 
length  to  allow  all  of  the  grain  to  work  out  before 
the  straw  is  passed  over. 

Some  raddles  are  agitated  by  being  driven  over 
irregularly  shaped  pulleys  which  produces  a  rapid 
jarring  motion.  This  has  the  effect  of  moving  the 
straws  slightly  among  themselves. 

The  point  where  the  straw  falls  on  the  raddle 
needs  special  attention.  The  straw  should  be  deliv- 
ered to  the  raddle  in  a  thin,  loose  mass,  for  when 
large  or  close  bunches  are  allowed  to  drop  on  it,  it 
carries  them  along  without  giving  them  a  chance  to 
separate  or  spread  out,  and  thus  prevents  the  kernels 
from  falling  through. 

As  the  straw  falls  on  the  slats  of  the  raddle,  the 
rapidly  moving  bars  give  the  straw  sudden  jar  or 


SCIENCE    OF   THRESHING.  3! 

jerk  and  have  a  tendency  to  tear  the  mass  or  layer  of 
straw  apart.  The  greater  part  of  the  separation  is 
done  at  this  point  where  the  straw  falls  on  the  raddle. 
The  operation  seems  to  be  more  effective  if  the  straw 
is  permitted  to  fall  a  little  distance  before  it  strikes 
the  raddle.  The  impetus  of  the  falling  straw  added 
to  the  force  of  the  blow  given  while  the  direction 
which  the  straw  takes  is  changed,  also  aids  in  the 
separation;  if  the  straw  is  moving  in  the  same  direc- 
tion as  the  raddle  when  it  comes  in  contact  with  it, 
the  jarring  and  pulling  apart  motion  is  eliminated, 
and  the  straw  passes  along  quietly  without  change 
of  direction  or  change  of  position  of  the  stalks  in 
reference  to  each  other,  so  that  the  kernels  are  not 
disentangled. 

THE  COMBINATION  OF  RACK  AND  RADDLE. 

In  the  combination  of  the  vibrating  rack  with  the 
traveling  .raddle,  the  straw  usually  passes  over  the 
rack  first  and  is  then  delivered  to  the  raddle;  the 
straw  is  pulled  apart  and  thinned  by  the  rapid  motion 
of  the  raddle,  which  disposes  of  the  straw  very 
quickly  and  usually  faster  than  it  is  delivered.  This 
pulling  apart  process  greatly  aids  separation  at  this 
point. 


CHAPTER  IV. 

GRAIN  CLEANING  MEMBERS 

In  separating  the  grain  from  the  straw,  a  large 
quantity  of  chaff  and  refuse  passes  out  with  the  ker- 
nels. This  is  disposed  of  by  passing  the  uncleaned 
grain  over  a  series  of  sieves,  through  which  a  current 
or  blast  of  air  is  forced.  The  combination  of  sieves 
and  blast  fan  is  called  the  cleaning  mill  or  shoe,  and 
takes  the  place  of  the  fanning  blanket  of  the  old 
threshing  floor  or  the  fanning  mill  of  recent  years. 

There  are  three  things  to  be  considered  in  refer- 
ence to  the  cleaning  mill  or  shoe,  on  which  its 
successful  working  depends,  namely,  the  sieves,  the 
blast,  and  the  sieve  motion.  The  sieves  should  be 
adapted  to  the  kind  of  grain  to  be  threshed  and  as 
few  as  will  do  the  work  should  be  used,  a  greater 
number  retarding  the  blast  and  catching  straw  and 
sticks.  The  blast  should  be  strong  enough  to  flow 
constantly  through  the  sieves,  even  when  the  latter 
are  heavily  loaded.  The  motion  of  the  sieves  should 
be  sufficient  to  insure  movement  of  the  chaff  and 
kernels  on  the  sieve  surface. 

THE  SIEVES. 

The  sieve  comprises  a  frame,  mainly  of  wood,  and 
a  woven  wire  or  sheet  metal  body.  The  best  prac- 
tice of  to-day  favors  perforated  or  corrugated  sheet 
metal  sieves,  although  the  wire  mesh  is  still  used. 

32 


SCIENCE    OF    THRESHING.  33 

A  properly  constructed  sieve  permits  the  grain  to 
fall  through  it,  passing  the  chaff  and  refuse  over  it, 
without  allowing  the  straw  and  sticks  to  be  retained 
in  the  meshes,  and  directs  the  blast  in  the  proper 
direction.  In  practice,  a  sieve  adapted  to  each  kind 
of  work  is  used,  though  some  combinations  of  sieves 
work  very  well  on  several  different  grains.  The 
usual  plan  is  to  permanently  secure  the  upper  sieve, 
called  the  chaffer,  it  being  of  sufficiently  large  mesh 
to  adapt  it  to  the  coarsest  grains.  The  lower  sieve 
or  sieves  are  interchangeably  secured  so  that  they  can 
be  varied  according  to  the  work  to  be  done. 

Adjustable  sieves  'are  constructed  to  change  the 
size  of  the  opening  of  the  meshes  to  suit  different 
kinds  of  grain,  the  usual  construction  being  a  frame  in 
which  are  hinged  cross  slats.  The  adjusting  of  the 
slats  changes  the  opening,  also  changes  the  angle 
of  the  blast  through  the  sieve.  When  the  slats  are 
tipped  back  the  openings  are  reduced  in  size,  and  the 
blast  directed  in  a  more  backward  direction. 

The  openings  in  the  sieve  must  be  large  enough  to 
permit  the  free  passage  of  the  clean  kernels,  and 
should  be  sufficient  in  number  not  to  retard  the  blast. 
If  the  openings  are  too  small  or  too  few  in  number, 
the  grain  accumulates  on  the  sieve  and  passes  over 
into  the  tailings  elevator,  by  which  it  is  carried  back 
to  the  cylinder.  This  greatly  reduces  the  capacity  of 
the  machine  as  it  needlessly  increases  the  amount  of 
grain  it  is  required  to  separate.  If  the  openings,  on 
the  other  hand  are  too  large,  they  permit  the  sticks 


34  SCIENCE    OF    THRESHING. 

and  straw  to  pass  out  with  the  grain,  causing  it  to  be 
dirty  and  poorly  cleaned. 

The  openings  should  be  so  shaped  as  to  direct  the 
flow  of  the  blast  in  the  proper  direction,  which  is 
approximately  at  right  angles  to  the  sieve  surface. 
This  prevents  the  blast  from  blowing  the  grain  along 
the  sieve  surface.  If  there  are  too  many  openings, 
— and  this  is  the  case  in  a  wire  sieve — too  much  of  a 
blast  passes  through;  this  causes  so  strong  a  current 
above  the  sieve  that  it  prevents  kernels  which  are 
lifted  from  the  surface,  from  falling  again  until  the 
rear  of  the  sieve  is  reached. 

The  sieves  should  be  stiff  and  rigid  so  as  not  to 
spring  at  the  center;  otherwise  the  motion  will  be  too 
violent  there  and  throw  the  grain  so  high  as  to  keep 
it  from  falling  through  the  sieve.  A  sieve  frame 
which  travels  two  inches  at  each  stroke  and  makes 
two  hundred  and  fifty  strokes  a  minute,  goes  five  hun- 
dred inches  every  minute ;  if  its  center  springs  an  inch, 
it  goes  three  inches  at  every  stroke,  or  seven  hundred 
and  fifty  feet  a  minute,  a  motion  which  may  be  alto- 
gether too  violent  for  that  part  of  the  grain  which 
falls  on  the  center  of  the  sieve. 

THE   FAN. 

A  fan  is  a  device  for  producing  a  blast  or  current 
of  air.  The  usual  form  used  in  separators  consists  of 
a  central  shaft  from  which  radiate  arms  which  carry 
blades  or  wings.  These  revolve  in  a  casing,  and  the 
rapid  motion  of  the  outer  ends  of  the  blades  forces 
the  air  to  rush  out  of  an  opening  in  the  side  of  the 


SCIENCE    OF   THRESHING.  35 

casing. 

This  air  is  replaced  by  a  current  which  enters  a 
central  opening  at  the  ends  of  the  casing. 

Fans  are  overblast  when  the  upper  blades  travel 
towards  the  outlet;  they  are  called  underblast  when 
the  lower  blades  move  toward  the  mouth. 

THE  BLAST. 

The  blast  is  an  important  feature  of  the  cleaning 
mill.  It  should  lift  the  chaff  and  light  matter  and 
prevent  it  from  falling  through  the  sieve  openings, 
and  at  the  same  time  maintain  a  continuous  flow 
through  the  sieve.  It  should  be  strongest  in  the 
sieve  openings,  and  light  above  the  sieve  surface. 
When  these  conditions  are  secured,  if  the  blast  lift  a 
kernel,  it  will  ascend  but  a  short  distance  before  it 
again  returns  to  the  sieve;  if  the  blast  were  as  strong 
above  the  sieve  as  at  the  meshes,  the  kernel  would 
be  blown  out  with  the  blast  and  wasted. 

To  obtain  these  conditions,  the  solid  or  blind 
portions  of  the  sieve  should  be  in  proper  proportion 
to  the  openings;  practice  establishes  this  at  about 
five  to  seven.  That  is  to  say,  the  solid  portion  of  the 
sieve  should  be  about  five-twelfths  of  the  surface,  and 
the  openings  should  be,  in,  the  aggregate,  about  seven- 
twelfths  of  the  surface.  It  will  be  observed  in  using 
a  sieve  of  these  proportions,  that  the  blast  will  be 
only  seven-twelfths  as  strong  just  above  the  surface 
as  in  the  meshes.  It  is  to  be  noted  that  this  state- 
ment is  more  strictly  correct  when  the  direction  of  the 
blast  is  at  about  right  angles  to  the  sieve. 


36  SCIENCE    OF    THRESHING. 

The  blast  should  be  sufficiently  strong  to  insure  its 
continual  flow  under  all  circumstances  and  conditions, 
but  not  fast  enough  to  blow  any  of  the  grain  over 
with  the  chaff. 

There  is  a  difference  between  a  blast  of  strong 
pressure  and  a  blast  of  high  speed.  A  current  of  air 
may  be  traveling  slowly,  and  still  go  with  force  and 
be  difficult  to  stop,  as  is  that  produced  from  a  slow 
moving  air-pump ;  or  it  may  be  moving  quite  rapidly 
but  with  no  particular  force  more  than  the  momentum 
produced  by  its  own  weight,  like  the  zephyr  of  a 
summer  day  or  the  breeze  from  a  lady's  fan.  The 
least  obstruction  would  stop  or  turn  such  a  blast. 
THE  KERNELS  OF  GRAIN  WILL  FALL  THROUGH  A 
BLAST  OF  ANY  PRESSURE  OR  STRENGTH,  BUT  WILL 
NOT  FALL  THROUGH  A  VERY  RAPIDLY  TRAVELING 
BLAST. 

The  chaff  is  easily  lifted  on  account  of  its  light 
weight.  To  do  good  work  then,  it  requires  a  mild 
or  slow  blast  delivered  with  strength  or  force.  This 
blast  should  be  spread  under  the  entire  surface  of  the 
sieve  and  be  made  to  flow  through  every  mesh.  It 
should  be  strongest  and  of  greatest  quantity  at  the 
front  end  of  the  sieve,  which  receives  the  grain  and 
chaff,  for  it  is  here  that  the  greatest  work  is  to  be 
done  in  lifting  the  sheet  of  chaff  intermingled  with 
grain.  It  should  decrease  in  quantity  and  pressure 
toward  the  rear  end  where  the  least  work  is  required. 
Thus  if  a  light  kernel  has  been  lifted  with  the  chaff 
at  the  front  end,  it  will  have  a  chance  to  fall  before 
reaching  the  rear  end  of  the  sieve.  If  the  blast  is 


SCIENCE    OF    THRESHING.  37 

made  to  pass  through  the  chaff,  as  soon  as  it  enters 
the  upper  sieve  it  will  lift  and  scatter  it,  the  lightest 
flying  out  first,  thus  giving  the  kernel  an  opportunity 
to  fall  through  the  sieve  much  more  quickly  and 
freely  than  if  the  blast  were  not  strong  enough  to 
keep  the  meshes  open  and  clear  of  chaff.  Besides,  if 
the  blast  ceases  to  flow  through  any  of  the  meshes, 
the  fine  dust  and  chaff  will  fall  through  and  cause  the 
second  sieve  to  be  overloaded,  and  thus  the  grain  may 
retain  a  part  of  the  chaff  and  dirt. 

SIEVE    MOTION. 

The  motion  of  the  shoe  should  be  sufficiently 
strong  and  rapid  to  move  the  grain  and  chaff  on  the 
surface  of  the  sieves.  Too  strong  a  motion  will 
interfere  with  the  kernels  falling  through  the  meshes 
properly,  and  cause  the  grain  to  be  carried  over,  either 
with  the  chaff  or  into  the  tailings  spout.  It  is  found  in 
practice  that  the  upper  sieve  or  chaffer  requires  a 
more  violent  and  positive  motion  than  the  lower 
sieves,  on  account  of  the  great  quantities  of  chaff 
and  cut  straw  to  be  carried.  For  this  reason  the 
chaffer  is  usually  placed  in  a  different  frame  and 
given  a  longer  stroke  while  the  remaining  sieves  have 
a  short  and  rapid  motion. 

The  coarser  and  looser  the  material  to  be  handled, 
the  longer  and  more  vigorous  the  motion  should  be. 
The  straw  rack  which  is  loaded  with  loose,  fluffy 
straw,  requires  quite  a  long  stroke  to  be  effective, 
while  the  conveyor  and  chaffer  sieves  need  less 
motion  and  the  shoe  sieves  still  less. 


38  SCIENCE    OF    THRESHING. 

It  will  be  seen  that  if  the  straw  rack  had  a  slight 
motion,  it  would  not  handle  or  scarcely  move  the 
straw  at  all,  while  if  the  conveyor  and  chaffer  sieves 
had  as  much  motion  as  the  straw  rack,  they  would 
throw  the  grain  so  fiercely  as  to  prevent  a  good 
portion  of  it  from  passing  through.  This  is  because 
of  the  difference  in  the  elasticity  or  springiness  of  the 
materials  to  be  moved.  It  is  thus  quite  essential  that 
the  motion  should  be  adapted  to  the  class  of  work  to 
be  done.  In  end  shake  sieves,  that  is,  where  the 
stroke  is  endwise  of  the  machine,  this  motion  should 
be  upwards  and  backwards  with  quite  an  uplift,  and 
should  be  just  strong  or  rapid  enough  to  cause  the 
grain  to  be  carried  along  as  quietly  as  possible. 

In  side  shake  sieves,  that  is,  where  the  motion  is 
sidewise  to  the  machine,  the  motion  should  be  suffi- 
ciently strong  and  long  to  cause  the  sieve  to  move 
continually  under  the  grain  and  chaff,  thereby  aiding 
the  blast  in  carrying  the  chaff  along  toward  the  rear. 

The  blast  may  be  at  a  greater  angle  from  the 
perpendicular  in  side  shake  sieves  than  in  end  shake 
sieves  as  it  is  the  only  means  of  carrying  the  chaff  and 
refuse  along  to  the  rear. 

In  the  end  shake  sieve,  the  upward  and  backward 
motion  assists  in  moving  the  mass. 

Side  shake  sieves  may  be  given  an  upward 
rocking  at  each  side,  as  the  stroke  is  finished. 
This  is  accomplished  by  using  comparatively  short 
hangers  and  adjusting  them  at  an  angle  (sidewise  to 
the  machine).  As  the  sieve  is  moved  sideways,  one 
side  will  continue  to  rise,  and  the  other  to  lower 


SCIENCE    OF   THRESHING.  39 

somewhat,  causing  it  to  give  the  grain  a  slight 
upward  motion  at  each  stroke.  This  motion  varies 
in  different  places  on  the  surface  of  the  sieve,  being 
nearly  parallel  thereto  at  the  center. 

The  blast  and  sieve  motion  should  be  properly 
gauged  one  by  the  other,  and  by  the  working  condi- 
tions. It  is  necessary  for  a  shoe  using  a  weak  blast 
to  be  given  a  greater  motion  to  assist  in  carrying  off 
the  refuse  and  chaff,  when  the  blast  is  overtaxed,  as 
when  an  undue  amount  of  chaff  and  cut  straw  loaded 
with  dust  isdelivered  to  it,  or  in  damp  threshing. 


CHAPTER  V. 
THE  DELIVERY  MEMBERS 

WIND   STACKERS 

The  use  of  an  air  blast  for  stacking  the  straw  has 
become  common.  The  air,  straw  and  chaff  are  blown 
from  the  interior  of  the  machine  by  a  suitable  fan 
through  a  pipe,  the  object  being  to  direct  the  blast 
so  that  a  stack  may  be  easily  formed. 

When  the  pneumatic  stacker  was  first  introduced 
the  item  of  power  was  an  important  one.  The  first 
fans  used  had  large  wings  running  at  a  high  rate  of 
speed,  and  it  is  safe  to  say  that  it  required  as  much 
power  to  operate  the  stacker  as  it  did  to  run  the 
rest  of  the  separator.  At  first  the  fans  were  belted 
to  run  from  1,000  to  1,700  revolutions  per  minute; 
the  enormous  power  required  to  do  this  either  stalled 
the  engine  or  slipped  the  belt  so  that  in  fact  the  fans 
were  driven  at  much  slower  speed. 

In  present  practice  the  fan  is  driven  at  from  300  to 
500  revolutions  per  minute  and  the  blades  of  the  fans 
have  been  reduced,  so  that  the  power  required  is 
greatly  lessened.  The  work  performed  by  the  fan 
of  the  wind  stacker  is  setting  the  air  and  straw  in 
motion  and  forcing  it  through  the  straw  pipe.  The 
more  air  set  in  motion  and  the  greater  speed  given  it, 
the  more  power  required.  The  weight  of  air  passing 

40 


SCIENCE    OF    THRESHING.  4! 

through  the  straw  pipe  exceeds  that  of  the  straw, 
that  is,  there  are  more  pounds  of  air  than  pounds  of 
straw  set  in  motion  by  the  fan.  So,  in  determining 
the  work  performed  by  the  fan,  the  item  of  air  can 
be  figured,  as  the  more  straw  there  is,  the  less  air 
there  is,  and  consequently  the  less  weight.  The 
actual  foot  pounds  or  horse  power  expended  is 
determined  as  follows:  Multiply  the  area  of  the 
straw  pipe  by  the  number  of  feet  the  air  travels  per 
minute;  multiply  this  by  the  pressure  required  to 
produce  this  speed;  the  result,  which  gives  the 
number  of  foot  pounds,  divided  by  33,000  is  the 
horse  power.  Thus,  the  area  of  the  usual  15  in. 
stacker  pipe  is  176  sq.  in.  A  pressure  of  one  ounce 
per  sq.  in.  gives  a  velocity  of  5.161  feet  per  second  to 
the  air.-  176X5.161=908,336  ounces,  which,  di- 
vided by  1 6,  the  number  of  ounces  in  a  pound,  equals 
56,271  foot  pounds.  Dividing  this  by  33,000,  the 
number  of  foot  pounds  in  a  horse  power,  equals  I J4 
horse  power  approximately.  At  this  velocity  and 
pressure  about  14  tons  of  air  and  straw  per  hour 
pass  through  a  15  inch  pipe  (of  which  about  ten 
tons  of  air  and  four  tons  of  straw  represent  a  fair 
average.)  There  is  of  course  more  dry  straw  blown 
through  in  a  given  time  than  wet  straw. 

Some  power  is  lost  by  leakage  around  the  fan  and 
at  its  center;  also  cutting  and  chopping  the  straw. 
A  slow  moving  fan  moving  a  large  amount  of  air 
steadily  is  better .  than  a  fast  turning  one,  as  the 
increased  friction  of  the  more  rapid  current  absorbs 
a  great  deal  of  energy.  Some  experiments  along  this 


42  SCIENCE    OF    THRESHING. 

line  strikingly  show  this  increase.  A  good  type  of 
fan  was  run  at  its  normal  slow  speed  of  approx- 
imately 400  revolutions  per  minute  and  furnished  the 
normal  pressure.  The  speed  was  then  gradually 
increased  one-quarter,  or  to  practically  500  revolu- 
tions per  minute.  It  was  found  that  the  pressure  had 
increased  about  16  2/3  %,  and  the  power  35  1/3  %, 
or  in  round  numbers,  an  increase  of  one-quarter  in 
speed  gave  an  increase  of  one-sixth  in  pressure  and 
used  one-third  more  power. 

HANDLING  THE   THRESHED   GRAIN. 

There  are  a  variety  of  weighers,  measurers,  sackers 
and  wagon  loaders  on  the  market  and  in  use  to 
handle  the  cleaned  grain  as  it  comes  from  the 
machine. 

Included  among  these  is  a  class  that  measures  the 
grain  as  it  is  threshed  and  registers  the  number  of 
bushels  as  delivered;  also  a  class  that  measures  the 
grain  instead  of  weighing  it,  and  keeps  a  tally  or 
record  of  the  amount.  There  is  also  a  short  sacker, 
requiring  a  man  to  operate  it,  which  aids  in  sacking 
the  grain,  and  a  wagon  loader  which  delivers  the 
grain  to  either  side  of  the  machine  without  making 
record  of  the  amount  handled. 


CHAPTER  VI. 

FEEDING 

Supplying  the  grain  or  feeding  should  be  done  as 
steadily  and  uniformly  as  possible  in  order  to  keep  a 
continuous  stream  of  grain  passing  through  the 
cylinder.  This  keeps  the  engine  working  with  uni- 
form steam  and  tension  on  the  belt. 

When  grain  is  fed  into  the  cylinder,  the  speed  of 
the  latter  is  checked.  As  soon  as  this  checking  is 
felt  on  the  main  drive  belt,  the  engine  speed  is 
decreased  until  the  governor  has  time  to  act  and,  by 
admitting  more  steam,  restore  the  normal  motion 
to  the  engine.  This  change  causes  the  engine  to  pull 
harder  on  the  belt.  If,  while  this  tension  is  on,  the 
cylinder  suddenly  runs  out  of  straw,  the  speed  at  once 
increases  in  obedience  to  the  extra  strain  on  the  belt, 
as  it  takes  a  little  time  to  communicate  this  change  of 
speed  to  the  governor  and  have  it  cut  off  the  steam. 
The  result  is  a  see-sawing  motion  every  time  that  a 
bundle  goes  into  the  machine,  unless  it  is  properly 
divided  and  lapped  on  the  preceding  bundle.  An 
entire  bundle,  especially  if  it  is  large  or  compact 
enough  to  slug,  should  never  be  allowed  to  enter  the 
cylinder. 

The  average  cylinder  teeth  are  about  three  inches 
long.  The  concave  teeth  occupy  about  one-third  of 

43 


44 


SCIENCE    OF   THRESHING. 


the  space  between  the  concave  and  cylinder  bars,  thus 
leaving  about  two  inches  through  which  the  bundle 
must  be  passed.  This  compressing  process  of  the 
teeth  consumes  a  large  amount  of  power.  A  five 
hundred  pound  cylinder  has  a  momentum  or  striking 
force  of  thirteen  hundred  and  twenty  tons.  This 
indicates  the  terrible  strain  on  the  machine  when  a 
bundle  is  fed  in  of  sufficient  size  to  stop  the  cylinder, 
although  this  does  not  often  happen.  But  the  power 
consumed  when  the  bundles  are  not  properly  divided 
up  is  enormous,  and  is  still  further  increased  when 
the  straw  is  damp  and  tough,  as  tough  and  pliable 
straw  clings  more  firmly  to  the  cylinder  teeth  than 
does  dry  and  brittle  straw. 


SELF-FEEDERS. 


Self-feeders  are  of  comparatively  recent  develop- 
ment, though  they  have  been  experimented  with  for 
several  years.  After  patient  study  and  many  unsuc- 
cessful trials,  the  feeder  and  band  cutter  has  reached 


SCIENCE    OF    THRESHING.  45 

a  degree  of  perfection  that  makes  it  a  desirable  part 
of  the  complete  threshing  rig. 

The  office  of  the  self-feeder  is  to  cut  the  bands, 
loosen  the  bundle,  dividing  it  in  a  sufficiently  thin 
body,  and  present  it  to  the  cylinder  in  a  manner  that 
will  not  permit  slugging  or  choking  of  the  cylinder. 
To  do  this  successfully  it  is  necessary  that  the  bundles 
should  be  drawn  out  or  elongated  endwise,  or  divided 
in  some  way  that  the  cylinder  may  not  receive  the 
whole  bundle  at  one  time.  The  usual  method  of 
accomplishing  this  is  to  pass  the  lower  part  of  the 
bundle  towards  the  cylinder  slowly  while  the  top  part 
has  its  speed  increased  by  some  faster  traveling  mech- 
anism above  it,  forcing  the  top  straws  ahead  while  the 
lower  ones  are  being  retarded  and  this  must  be  accom- 
plished before  the  bundle  reaches  the  cylinder.  The 
more  thoroughly  this  is  done  the  better  the  feeder  and 
the  machine  seem  to  work. 

There  has  been  some  experimenting  with  governors 
to  regulate  the  amount  being  fed  to  the  machine  and 
they  are  being  used  with  more  or  less  success.  Some 
depend  on  the  speed  of  the  cylinder  to  disengage  a 
mechanism  whereby  the  feeder  is  thrown  out  of  gear 
when  the  speed  is  reduced  below  a  predetermined 
number  of  revolutions  per  minute.  Others  regulate 
by  the  amount  or  bulk  of  the  traveling  column  of 
straw. 

The  bundles  in  most  feeders  are  first  deposited  on 
the  carrier,  on  which  they  are  carried  along  to  the 
band  cutting  device  by  means  of  a  raddle  constructed 
of  belting  with  laterally  secured  slats,  or  a  canvas  cov- 


46  SCIENCE    OF   THRESHING. 

ered  table.  As  the  bundles  move  towards  the 
cylinder,  they  are  acted  upon  by  the  band  cutters, 
which  should  be  sufficiently  near  together  and  travel 
close  enough  to  the  table,  to  insure  all  the  bands 
being  cut.  It  is  also  necessary  that  the  bundles 
should  be  thoroughly  picked  apart  and  loosened  up 
before  reaching  the  cylinder.  The  band  cutters  in 
most  of  the  feeders  perform  this  office  also,  by 
passing  the  knives  rapidly  into  the  bundle  among  the 
straws  in  such  a  manner  as  to  throw  the  top  straws 
ahead  toward  the  cylinder. 

A  separator  with  a  properly  constructed  self- 
feeder  will  require  but  very  little  more  power  to 
thresh  a  given  amount  of  grain  in  a  given  time,  as 
it  divides  up  the  bundles  and  feeds  clear  across  the 
cylinder  much  better  than  is  done  by  hand.  But  with 
the  use  of  self-feeders  the  pitchers  usually  pass 
the  bundles  along  a  little  faster  because  they  do  not 
have  to  use  the  same  caution  about  placing  them  on 
the  table  as  they  do  in  hand  feeding.  The  only  thing 
they  need  to  observe  is  the  amount  or  quantity  being 
handled. 


CHAPTER  VII. 

OPERATION 

In  operation  the  separator,  like  any  other  machine, 
does  its  work  best  when  properly  adjusted  and 
managed.  There  is  no  machine  which  has  a  more 
varied  scope  of  work  or  which  has  to  encounter  so 
many  conditions.  It  is  rare  that  there  are  two  fields 
of  grain  grown,  ripened,  cut  and  handled  under  like 
conditions;  one  may  be  in  a  condition  to  shell  from 
the  straw  readily,  while  in  another  the  kernels  may 
cling  to  the  head  so  as  to  make  it  almost  impossible 
to  dislodge  them.  One  stack  may  be  brittle  and  break 
too  readily,  while  the  next  may  pass  through  without 
this  annoyance.  One  kind  may  be  stiff  and  stubborn 
and  another  soft  and  pliable;  one  lot  may  have  many 
blades  or  leaves  on  the  stalks,  another  only  the  plain 
stalks  and  heads;  one  kind  may  have  a  light,  fluffy 
chaff  and  heavy  kernels,  and  another  the  reverse, 
heavy  chaff  filled  with  sap  and  light  kernels. 
Some  fields  are  filled  with  weeds  and  foreign  matter 
which  the  machine  is  expected  to  distinguish  and 
separate  from  the  grain. 

Then  again,  there  are  conditions  of  the  weather 
which  appreciably  influence  the  working  of  the 
machine,  and  cause  a  wide  variation  in  the  amount 
of  power  required.  Some  days  are  bright  and  sun- 
shiny, others  damp  and  foggy.  Some  are  warm  or 

47 


48  SCIENCE    OF    THRESHING. 

hot,  others  cold.  There  may  be  a  hard  wind  blowing 
or  there  may  be  none.  All  these  various  conditions 
affect  the  machine,  each  in  a  peculiar  way.  The 
operator  is  expected  to  save  every  kernel,  perfectly 
cleaned,  and  do  many  other  things  equally  well  nigh 
impossible,  notwithstanding  these  varied  conditions. 
The  man  who  best  understands  the  machine  and  its 
workings  will  come  the  nearest  to  perfection  in 
managing  it. 

As  before  stated,  the  cylinder  is  a  vital  part  and 
should  receive  special  attention  and  be  kept  in  good 
condition.  If  it  is  out  of  balance  appreciably,  it 
should  be  taken  from  the  machine  and  set  on  the 
straight  edges,  as  explained  before,  and  restored  to 
balance  by  inserting  counterbalancing  weights  in  the 
light  side.  The  boxes  should  not  run  too  tight,  as 
the  extra  friction  consumes  a  large  amount  of  power. 

The  teeth  should  not  be  allowed  to  become  so 
worn  and  rounded  as  not  to  draw  the  straw  into  the 
machine  freely.  By  replacing  the  worn  by  new  teeth, 
evenly  distributed  around  the  cylinder,  the  straw  will 
be  readily  pulled  in  and  the  grain  threshed  clean. 
Care  should  be  taken  to  keep  the  teeth  properly 
spaced;  any  bent  ones  may  be  trued  up  with  the 
tooth  straightener,  or  by  the  use  of  a  heavy  hammer. 

The  cracking  of  grain  is  usually  caused  by  one  or 
more  cylinder  teeth  running  so  close  to  the  concave 
bottom,  or  teeth,  as  not  to  permit  a  whole  kernel  of 
grain  to  pass ;  the  resultant  wedging  cracks  or  breaks 
the  grain.  Another  cause  is  the  repeated  passing  of 


SCIENCE    OF    THRESHING.  49 

the  grain  through  the  cylinder  by  the  tailings  elevator. 
Each  time  a  kernel  receives  a  blow  from  a  cylinder 
tooth  it  is  partially  disintegrated,  and  many  blows 
crack  or  break  it  open. 

Only  enough  concave  teeth  should  be  used  to 
retard  the  passage  of  the  straw  through  the  concave 
a  sufficient  length  of  time  to  allow  all  the  kernels  to 
be  loosened.  More  teeth  than  are  required  to  do 
this  consume  power  unnecessarily  as  well  as  cut  up 
the  straw  to  such  an  extent  as  to  interfere  with  the 
proper  workings  of  the  separating  and  cleaning 
mechanisms.  The  machine  will  often  do  better 
work  with  two  or  four  rows  of  teeth  than  with 
more.  In  handling  oats,  two  rows  of  teeth  are  com- 
monly enough,  except  when  the  kernel  is  small  and 
light  and  the  oats,  which  may  have  been  cut  when 
green,  seem  tough  and  cling  to  the  heads;  in  this 
case  high  speed  in  the  cylinder  and  more  rows  of 
teeth  in  the  concave  are  required  to  loosen  all  of  the 
kernels  from  the  straw. 

For  use  in  sections  of  the  country  where  flax  is 
grown  the  concave  should  be  specially  designed  with 
teeth  set  near  together,  as  some  conditions  require 
very  close  adjustment  to  -enable  them  to  break  open 
the  balls  containing  the  seeds.  Under  some  condi- 
tions, the  ball  is  often  found  to  be  saturated  with  an 
oily,  gummy  substance  which  makes  it  very  tough; 
it  is  then  liable  to  break  off  from  the  stalks  and  pass 
whole  through  the  machine.  To  meet  such  condi- 
tions, use  all  the  concave  teeth  possible  and  run  the 
cylinder  at  a  high  rate  of  speed,  arranging  the  parts 


50  SCIENCE    OF    THRESHING. 

at  the  rear  of  the  machine  to  return  the  unbroken 
balls  through  the  tailings  elevator. 

In  threshing  barley,  plenty  of  concave  teeth  and  a 
high  cylinder  speed  break  off  or  "nub"  the  beard 
effectually. 

The  grate,  as  before  indicated,  which  lies  back  of 
the  cylinder,  should  have  its  rear  edge  raised  so  that 
the  straw  and  grain,  as  it  comes  from  the  cylinder, 
should  strike  its  face  at  a  slight  angle.  This  keeps  it 
clean  and  prevents  it  from  loading  up  with  thick  or 
brittle  straw. 

The  beater  should  be  in  a  position  for  the  straw 
and  grain,  as  it  comes  from  the  cylinder,  to  pass  it 
without  changing  its  course  too  much;  that  is,  it 
should  be  so  adjusted  that  the  straw  will  not  strike  it 
near  its  center,  as  the  straw  would  then  have  to 
change  its  course  to  pass  around  it. 

If  the  beater  is  arranged  to  allow  the  straw  to  pass 
under  it,  the  wings  of  the  beater  or  beater  boards 
should  have  just  sufficient  contact  with  the  straw  to 
keep  it  moving. 

In  the  scheme  of  separation,  the  first  essential 
feature  is  to  have  the  threshing  members  deliver  the 
straw  to  the  separating  devices  with  the  kernels  all 
threshed  from  the  heads  and  the  straw  unbroken. 
Whole  straw  will  not  pack  as  closely  and  hold  the 
kernels  in  consequence  as  does  broken  or  cut  straw. 
Stalks  that  are  heavily  loaded  with  leaves  form  a  com- 
pact, homogeneous  mass  which  retains  the  kernels, 
and  are  consequently  hard  to  separate. 

Oats  are   frequently  hard  to  separate.      In  some 


SCIENCE    OF   THRESHING.  51 

sections  of  the  country  rust  is  prevalent;  this  forms 
on  the  stalks  and  leaves  before  they  are  harvested, 
making  them  brittle,  while  it  blights  the  kernels, 
which  are,  in  consequence,  light.  The  rust  on  the 
stalks  has  a  certain  clinging  roughness  that  causes 
them  to  adhere  to  each  other  and  therefore  retards 
the  disintegrating  effect  of  the  rack  or  raddle  which 
does  not  move  them  among  themselves  but  allows 
them  to  travel  along  in  a  compact  mass.  In  such 
case,  all  that  can  be  done  is  to  adjust  the  machine  to 
the  best  advantage,  run  at  good  speed  and  regulate 
carefully  the  amount  fed  to  the  other  conditions. 

Rye  Is  usually  very  easily  separated,  as  the  stalks 
are  stiff,  and  comparatively  little  chaff  and  dirt  is 
found.  In  some  instances  the  straw  is  so  loose  and 
fluffy  as  to  prevent  it  being  worked  back  fast  enough 
by  the  separating  devices,  thereby  causing  the  body 
of  the  machine  to  choke  up.  In  case  this  happens,  cut 
the  straw  up  by  inserting  more  teeth  in  the  concave. 
By  weighting  down  the  check  board  of  a  vibrating 
or  rack  machine  it  will  compress  the  straw  somewhat 
and  give  the  table  a  better  chance  to  handle  it.  A 
convenient  way  of  doing  this  is  by  fastening  a  piece 
of  wood  or  iron  lengthwise  along  its  back  by  suitable 
screws  or  bolts. 

As  stated  before,  it  is  quite  essential  that  the 
machine  stand  quite  still  on  its  truck  while  in  opera- 
tion. There  is  a  great  difference  between  the  opera- 
tion of  the  machine  when  the  frame  work  is  standing 
still  and  the  mechanisms  have  their  full  motion,  and 


52  SCIENCE    OF    THRESHING. 

its  working  when  the  frame  does  a  part  of  the 
moving,  which  the  mechanisms  complete. 

There  is  another  reason  why  the  separator  should 
be  made  to  stand  still.  When  the  engine  is  running, 
one  part  of  the  drive  belt  is  drawn  tight  while  the 
other  is  slack.  The  harder  the  engine  is  being  driven, 
the  tighter  will  the  belt  be  drawn;  if  the  separator 
is  rocking  on  its  trucks  to  and  from  the  engine  it  will 
take  up  some  of  the  slack  of  the  belt  as  it  sways 
toward  the  engine  and  when  moving  backward  away 
from  the  engine  the  belt  will  either  have  to  stretch 
or  slip  upon  the  pulley,  as  it  cannot  change  the  speed 
of  the  cylinder.  As  the  slack  has  already  been  taken 
up  it  is  very  likely  to  slip,  an  action  which  is  very 
hard  on  the  pulley  lagging,  and  on  the  belt,  and 
which  wastes  a  great  deal  of  power.  This  slipping 
and  straining  of  the  belt  is  greatly  augmented  if  the 
engine  also  moves  upon  its  trucks,  as  the  vibrations 
of  the  two  machines  will  not  be  the  same,  and  when 
one  is  rocking  in  one  direction,  and  the  other  in  the 
opposite  direction,  there  will  be  double  the  pull  on 
the  belt.  If  a  horse  power  is  used,  there  is  the  same 
need  for  the  separator  to  stand  still,  as  the  strain 
from  the  oscillations  and  vibrations  are  very  severe 
on  the  tumbling  rods. 

If  the  separator  fails  to  take  the  grain  out  of  the 
straw  properly,  it  is  usually  because  of  one  or  more 
of  the  following  reasons,  viz. : 

The  separator  is  not  standing  still  on  its  trucks; 
it  is  not  running  at  the  proper  speed;  the  cylinder 
fails  to  thresh  all  the  kernels  out  of  the  heads;  the 


SCIENCE   OF   THRESHING.  53 

separating  device  or  shoe  is  not  level;  or  the  machine 
is  being  crowded  beyond  its  capacity. 

The  shoe  or  cleaning  mill  should  receive  special 
study  by  anyone  who  intends  to  make  threshing  a 
success.  Though  the  device  appears  very  simple,  it 
has  many  features,  as  already  stated,  which  are  not 
generally  understood. 

The  motion  of  the  shoe  varies  in  different 
machines.  In  some  it  is  as  short  as  five-eighths  of  an 
inch,  in  others  it  is  four  inches;  though  there  is  not 
so  much  speed  variance  in  the  motion  of  the  upper 
sieve  or  chaffer,  which  generally  is  from  three  to  four 
inches.  The  following  rule  is  as  close  to  a  correct 
expression  of  the  true  principle  of  its  working  as  can 
be  stated: 

"The  shorter  the  stroke,  the  more  vibrations  per 
minute  are  required;  the  longer  the  stroke,  the  fewer 
vibrations  per  minute  are  required." 

The  speed  should  be  just  strong  and  quick  enough 
to  throw  the  straw  but  slightly  at  the  upper  finish  of 
the  stroke;  if  it  does  more  than  this,  it  will  carry  or 
throw  the  grain,  as  well  as  the  dirt,  and  a  part  of  it 
will  pass  out  with  the  chaff.  If  the  motion  is  not 
strong  enough  to  cause  the  grain  to  leave  the  upper 
surface  of  the  sieve  slightly  at  each  stroke,  the 
meshes  become  filled  with  grain  and  chaff,  and  the 
sieve  or  chaffer  becomes  choked  to  such  an  extent  as 
to  allow  but  little  to  pass  through.  If  the  mechan- 
ism is  such  that  the  upper  part  of  the  stroke  is  strong 
and  quick,  while  the  lower  part  is  slow  and  gentle,  it 


54  SCIENCE    OF   THRESHING. 

is  all  the  better,  as  the  upper  part  of  the  movement 
will  do  the  throwing  and  agitating,  while  the  slow 
part  of  the  stroke  will  allow  the  sieve  time  to  come  to 
rest  for  an  instant,  thereby  permitting  the  kernels  to 
fall  through. 

The  boxes  and  connections  that  operate  the  shoe 
should  be  kept  in  good  order  and  not  permitted  to 
work  loose,  as  the  lost  motion  causes  a  pounding  that 
jars  the  sieve,  which  springs  and  trembles;  this 
impedes  the  passage  of  the  grain. 


CHAPTER  VIII. 


THE  BLAST 

The  blast  requires  its  share  of  attention,  and  when 
it  is  once  thoroughly  understood  and  mastered,  it 
becomes  an  obedient  servant  capable  of  accom- 
plishing good  work.  But  few  changes  have  been 
made  in  the  blast  fans  since  they  were  first  used  in 
separators.  They  have  faults  as  well  as  virtues;  they 
do  not  always  send  the  proper  amount  of  blast  just 
where  it  is  intended  they  should  or  where  it  is  needed 
the  most. 

There  is  a  great  difference  in  the  condition  of  the 
material  which  the  shoe  has  to  handle  at  different 
times,  each  section  of  the  country  furnishing  a  partic- 
ular kind  or  quality  of  grain  to  be  threshed.  In  parts 
of  the  country  where  spring  wheat  is  raised,  there  is 
more  work  for  the  shoe  to  do,  as  there  is  more  chaff ; 
the  straw,  as  it  is  stiff  and  hard  to  thresh,  breaks  up 
more  than  does  that  of  the  winter  wheat  raised  in 
other  sections  of  the  country.  Though  the  kernels 
of  spring  wheat  are  not  much  heavier  than  the 
berries  of  the  winter  variety,  the  chaff  and  dust  from 
the  former  is  much  more  dense  and  weighty  than 
from  the  latter,  requiring  more  than  double  the 
pressure  of  blast  to  penetrate  and  lift  it. 

The  cylinder  and  concave  should  be  adjusted  to 

55 


56  SCIENCE    OF    THRESHING. 

get  the  grain  out  with  as  little  cutting  up  of  the  straw 
as  possible,  thereby  relieving  the  shoe  of  an  undue 
amount  of  work. 

As  the  grain  and  chaff  are  delivered  to  the  front 
end  of  the  chaffer,  the  kernels  are  more  or  less 
thoroughly  intermingled  with  the  refuse,  the  mixed 
mass  being  of  a  depth  and  quality  dependent  on  the 
amount  being  threshed.  It  is  plain  that  if  the  meshes 
of  the  chaffer  are  not  large  enough  to  let  the  whole 
mass  through,  the  most  of  the  kernels  will  be  carried 
along  with  the  chaff  and  dirt  by  the  action  of  the 
chaffer  to  the  rear  end.  But  force  a  little  blast 
through  and  watch  the  result;  as  the  blast  comes 
through  the  meshes,  it  lifts  grain,  straw  and  all. 
The  kernels  at  the  bottom  of  the  mass  will  fall 
of  their  own  weight  through  the  sieve.  As  the 
blast  continues  on  its  way  up  through  and  between 
the  different  particles  of  the  mass,  it  loosens  and  sepa- 
rates it,  carrying  the  lightest  bits  farthest,  and 
allowing  the  others  to  fall  of  their  own  weight.  By 
watching  the  blast  still  longer  it  will  be  noticed  that 
the  particles  which  are  traveling  through  the  air  are 
entirely  free  from  contact  with  each  other,  every 
particle  seeming  to  try  to  avoid  its  neighbors  as  much 
as  possible.  There  are  never  any  bunches  clinging 
together,  but  the  mass  is  thoroughly  divided,  thus 
producing  the  very  best  conditions  for  separating  the 
kernels  from  the  chaff. 

The  blast  should  be  strong  enough  at  the  front  of 
the  sieve  to  always  flow  through  the  very  first 


SCIENCE    OF    THRESHING.  57 

meshes  with  sufficient  force  to  keep  them  cleared  and 
to  itself  pass  up  through  the  layer  of  chaff  and  grain 
as  it  passes  along;  but  it  should  not  blow  fast  enough 
to  lift  the  light  kernels  very  high.  There  is  a  differ- 
ence between  strength  of  blast  and  speed  of  blast. 
The  blast  should  have  strength,  but  not  much  speed. 
A  horse  might  be  very  strong  and  able  to  move  a 
heavy  load,  but  not  move  it  very  fast.  The  horse 
would  then  be  able  to  go  at  a  constant  and  uniform 
speed  whether  loaded  heavily  or  lightly.  So  the 
blast  in  the  shoe  should  be  able  to  move  at  its  regular, 
constant  speed,  regardless  of  the  amount  of  grain  to 
be  handled.  It  is  plain  that  it  should  be  the  strongest 
at  the  front  end  of  the  chaffer  where  the  load  is 
heaviest,  the  chaff  being  mixed  with  the  grain  and 
packed  together  at  that  point.  After  the  blast  has 
once  penetrated  the  layer  and  has  lifted  the  chaff  up 
in  the  air  it  does  not  need  as  strong  a  blast  to  keep  it 
there.  In  some  wrongly  constructed  chaffers,  the 
reverse  conditions  are  found;  the  blast  being 
strongest  at  the  rear  end  of  the  chaffer  and  weakest 
at  the  front  end.  In  such  cases,  the  heavier  the  load 
of  chaff  which  comes  in  at  the  front  end,  the  harder 
the  blast  will  be  at  the  rear,  for  as  soon  as  a  little  too 
much  grain  and  chaff  enter  the  front  end  and  clog  the 
meshes,  the  blast  ceases  to  escape  there  and  is  forced 
along  under  the  sieve  to  its  rear  end;  here  it  is 
confined  and  deflected  upward  by  the  bottom  of  the 
shoe,  escaping  through  the  rear  meshes  with  force 
enough  to  carry  kernels  and  all  along  with  it. 

If  a  shoe  is  found  in  this  condition,  the  remedy  is 


58  SCIENCE    OF    THRESHING. 

to  arrange  the  blast  or  deflecting  boards  in  such  a 
manner  as  to  cause  the  blast  to  strike  the  front  end 
more  forcibly. 

To  aid  in  this  adjustment,  it  will  be  well  to  consider 
first,  some  of  the  peculiarities  of  the  fan  and  its 
action  on  the  air.  As  it  revolves  the  wings  make  the 
air  revolve  along  with  it.  As  each  wing  passes  the 
outlet,  a  small  portion  of  the  air  is  thrown  off  by 
centrifugal  force,  other  air  coming  in  through  the 
inlet  to  take  its  place  in  the  center  of  the  fan. 

As  the  fan  revolves  there  is  a  slight  increase  of 
pressure  of  the  air  against  the  front  side  of  the  wing, 
and  a  corresponding  decrease  along  the  rear  side,  the 
sum  of  these  plus  and  minus  pressures  being  nearly 
equal  to  the  atmospheric  pressure. 

As  each  wing  passes  the  outlet  opening  in  the  shoe 
the  air  starts  to  rush  in  behind  the  wing  from  the 
shoe  to  fill  the  slight  or  partial  vacuum  on  the  rear  of 
the  wing.  A  small  portion  thus  enters  the  fan  casing; 
the  next  wing  as  it  comes  round,  has  a  tendency  to 
force  this  intruding  portion  back  before  it  has  entered 
very  far.  This  alternate  rarefaction  and  compressing 
action  of  the  fan  causes  the  low  vibrating  or  humming 
sound  heard  in  fast  running  fans.  Now  this  action  of 
the  air  is  not  uniform  along  the  entire  length  of  the 
wing.  The  most  air  is  forced  out  at  the  center  of  the 
shoe,  which  materially  affects  the  action  of  the  blast 
through  the  sieves. 

When  a  fan  whose  casing  is  open  at  both  ends  to 
admit  air,  is  in  motion,  the  two  opposite  moving  col- 


SCIENCE    OF    THRESHING.  59 

umns  of  air  rushing  in  from  either  end  meet  at  about 
the  center.  This  meeting  of  the  opposing  blasts 
increases  the  pressure  somewhat  at  this  central  point, 
consequently  the  fan  delivers  more  freely  at  the  center 
of  the  outlet;  further,  the  air  rushes  in  more  freely 
behind  the  ends  of  the  wing  as  it  passes  the  outlet  as 
the  pressure  or  vacuum  is  greater  there  than  at  the 
center  of  the  wing;  therefore,  the  air  passes  from  the 
sieves  into  the  fan  near  the  ends  of  the  wings,  instead 
of  from  the  fan  through  the  sieves.  This  motion  is 
more  marked  in  long  than  in  short  fans,  therefore  in 
wide  than  narrow  machines. 

A  further  explanation  of  this  usually  unrecognized 
phenomenon  is  this :  As  the  air  rushes  from  the  ends 
towards  the  center  of  the  fan,  there  is  little  side  pres- 
sure towards  the  sieves  at  the  ends  of  the  fans  and  the 
extra  pressure  in  the  sieves  forces  the  air  back  into  the 
fan;  that  is,  the  air,  for  a  little  distance  from  the  fan 
ends,  travels  in  the  wrong  direction ;  as  the  air  comes 
from  the  center  of  the  fan,  it  thus  swings  back  upon 
itself,  forming  an  eddy.  Should  this  counter  current 
be  strong  enough,  it  results  in  carrying  some  of  the 
grain  along  with  it  into  the  fan.  This  effect  is  so 
marked  in  some  machines  that  the  corners  of  the  fan 
are  worn  by  striking  the  grain  blowrn  in  by  this 
motion  of  the  blast.  This  effects  the  perfect  cleaning, 
as  the  direction  of  the  blast  is  down  at  the  corners 
of  the  sieves,  thereby  carrying  the  chaff  and  dirt  into 
the  grain. 

This  whirling  motion  can  be  tested  in  any  machine 
by  taking  the  sieves  out  and  running  the  machine 


60  SCIENCE    OF    THRESHING. 

empty.  When  the  machine  is  in  motion,  take  a  cane 
or  stick  of -convenient  length  and  fasten  one  end  of  a 
ribbon  four  or  five  inches  long  to  one  extremity.  If 
held  in  the  blast  near  the  fan  outlet,  the  ribbon  will 
indicate  the  way  the  current  of  air  is  moving. 

Further  study  of  the  blast  will  show  that  its  direc- 
tion is  not  in  a  direct  line  from  the  point  of  delivery 
of  the  fan  along  the  stationary  blast  boards  at  the  top 
or  bottom,  towards  the  sieves,  but  tends  to  follow  the 
curve  of  the  fan  casing  until  it  comes  against  the 
blast  board.  Furthermore,  in  the  case  of  an  under- 
blast  fan,  the  blast  does  not  leave  the  fan  and  travel 
in  a  straight  line  along  the  bottom  board  towards  the 
sieves,  but  extends  in  a  thin  sharply  defined  current 
along  near  the  fan,  and  increases  slightly  in  thickness 
until  it  reaches  the  top  blast  board,  from  which  it  is 
deflected  down  and  back. 

The  slight  compression  of  the  air  at  the  center, 
makes  it  veer  off  at  an  angle  towards  each  corner,  so 
that  it  blows  harder  at  the  rear  corners  than  it  does 
at  the  central  portion. 

Two  or  three  narrow  wind  boards  one  or  two 
inches  wide,  placed  parallel  to  each  other  and  the  fan 
in  the  forward  part  of  the  shoe  below  the  sieves, 
greatly  aid  in  equalizing  and  adjusting  the  blast. 
They  should  be  set  at  an  angle  which  will  deflect  the 
blast  toward  the  forward  part  of  the  sieves  and 
should  be  near  enough  together  to  require  a  little 
pressure  to  force  the  blast  between  them.  This 
arrangement  makes  the  air  pass  out  along  the  entire 
length  of  the  fan  opening  to  relieve  the  pressure  on 


SCIENCE    OF    THRESHING.  6l 

the  fan  side,  and  will  tend  to  make  the  blast  uniform 
for  the  entire  width  of  the  sieve. 

As  before  stated  there  are  a  great  variety  of  sieves, 
the  woven  wire  ones  having  the  preference  in  former 
years.  They  admit  the  blast  very  freely  and  the 
straws  run  through  the  meshes  and  fill  them  up,  so 
they  are  in  some  disfavor  now.  The  present  ten- 
dency is  toward  sheet  metal  sieves  having  either  a 
plain  perforated  surface  or  irregular  lips  and  corru- 
gations and  lips.  Chaffers  are  frequently  made  of 
wooden  slats  set  at  an  angle,  or  with  plain  wood, 
perforated  at  an  angle  to  the  surface. 

The  angle  of  the  blast  as  it  passes  through  the 
sieve  should  be  upward  rather  than  backward.  The 
reason  is  that  a  kernel  will  fall  through  a  perpendic- 
ular blast  better  than  through  an  angularly  directed 
one,  and  a  perpendicular  blast  also  lifts  the  chaff 
from  the  sieve  better. 

The  correct  direction  is  given  the  blast  by  proper 
adjustment  of  the  lip  or  slat  forming  the  sieve  meshes, 
the  blast  taking  its  direction  from  the  lip. 

The  holes  or  meshes  should  be  only  large  enough 
to  allow  the  grain  to  pass  through  freely.  When  the 
sieve  is  properly  constructed  and  the  blast  properly 
adjusted,  there  need  be  no  waste  and  the  grain  will  be 
well  cleaned.  When  the  shoe  is  working  properly, 
there  will  be  a  very  small  quantity  of  tailings  to 
return  to  the  cylinder.  (Tailings,  so-called,  are  the 
grain  and  chaff  which  did  not  go  through  the  sieves, 
but  are  passed  over  the  chaffer.)  That  this  is  so  will 
be  seen  if  it  is  remembered  that  when  the  blast  strikes 


62  SCIENCE   OF   THRESHING. 

every  mesh  in  the  chaffer  properly,  it  will  prevent  any 
chaff  from  passing  through  and  will  blow  it  into  the 
straw  to  be  carried  away  with  it.  Besides,  if  the 
chaffer  is  properly  constructed  and  has  the  right 
motion,  as  soon  as  the  blast  clears  the  forward 
meshes  of  chaff,  the  grain  will  fall  through  at  once, 
and  will  then  have  the  entire  length  of  the  sieve  to 
travel  over  before  reaching  the  tailings  spout,  so  that 
there  will  be  little  chance  of  its  being  carried  around 
with  the  tailings.  This  is  the  crucial  test  of  a 
properly  adjusted  shoe,  for  if  the  blast  does  not  pass 
through  the  layer  of  grain  and  chaff  until  it  has 
passed  half  way  along  the  sieve,  or  more,  it  is  plain 
that  a  part  of  the  chaff  has  been  sifting  through  the 
sieve  where  there  is  no  blast  felt.  The  chaff  will  then 
find  its  exit  along  the  next  loweY  sieve  to  the  tailings 
spout.  A  portion  of  the  grain  cannot  pass  through 
the  chaffer  at  the  front  end,  but  is  carried  along  with 
the  chaff  to  the  point  where  the  blast  first  affects  it. 
This  may  be  so  near  the  tailings  spout  as  to  cause  the 
grain  to  be  carried  over  into  the  straw,  or  to  go  back 
to  the  cylinder  with  the  tailings,  thus  overloading  the 
elevator  and  unduly  taxing  the  capacity  of  the  sepa- 
rating and  cleaning  devices,  and  this  continued  return 
of  the  kernels  to  the  cylinder  is  liable  to  crack  or 
crush  them.  As  few  sieves  as  possible  should  be  used. 
Oats  usually  require  only  one.  In  weedy  wheat,  in 
some  instances,  a  second  sieve  in  the  shoe  will 
improve  the  cleaning.  Flax,  if  at  all  weedy,  may  be 
run  through  two  sieves  below  the  chaffer.  The  mis- 
take is  often  made  of  trying  to  run  flax  through  a 


SCIENCE    OF    THRESHING.  63 

sieve  with  too  small  meshes,  thus  causing  it  to  pass 
over  the  tailings  spout  and  increasing  the  impedance 
of  the  blast.  Some  kinds  of  flax  have  larger  seed 
than  do  others,  and  this  must  be  remembered  in 
adjusting  the  mill. 

In  fast  flax  threshing,  the  most  satisfactory  work 
can  be  done  by  using  a  finishing  sieve  (of  perforated 
sheet  metal,  not  wire)  having  meshes  three-sixteenths 
of  an  inch  across. 


CHAPTER  IX. 
BELTS 

The  success  of  a  machine  depends  largely  on  the 
belts.  Their  proper  care,  management  and  adjust- 
ment are  of  importance. 

Their  material  should  be  of  the  best  quality.  If 
leather,  they  should  run  with  the  grain  or  smooth  side 
to  the  pulley,  as  they  will  run  more  easily,  transmit 
more  power,  and  last  longer.  They  will  run  more 
freely  because  the  flesh  or  rough  side  will  expand 
more  easily  and  adjust  itself  to  the  curve  of  the 
pulley  in  running  around  it,  thereby  adding  to  the 
life  of  the  belt.  The  smooth  side  will  transmit  more 
power  because  it  brings  more  surface  into  actual 
contact  with  the  pulley. 

Belts  should  be  run  just  tight  enough  to  perform 
the  work  without  slipping,  for  power  consumed  in 
slipping  is  lost.  A  belt  that  slips,  tends  to  partially 
run  off  the  pulley  and  soon  wears  out  the  pulley 
facings. 

If  belts  become  dry  and  hard,  they  should  have  a 
dressing  of  neatsfoot  oil  with  a  little  rosin  mixed  in 
it.  Enough  rosin  should  not  be  used  to  leave  the 
surface  of  the  belt  in  a  sticky  condition.  A  pliable 
belt  will  transmit  more  power  than  a  belt  that  is  dry 
and  hard. 

Rubber  is  used  quite  extensively  in  some  places  and 


SCIENCE    OF    THRESHING.  65 

when  of  the  best  grade  is  very  economical,  as  its  first 
cost  is  less  than  that  of  the  best  grades  of  leather. 
Chain  or  link  belting  is  sometimes  used  and  in  some 
places  is  preferable  to  any  other.  It  never  slips  or 
runs  off,  and  does  not  become  unlaced.  When  link 
belting  is  used  it  should  not  be  run  when  too  tight  as 
it  causes  a  trembling  or  jarring  vibration  as  each  link 
passes  the  sprocket. 

LACING  A  BELT. 

There  is  a  right  and  a  wrong  way  to  lace  a  belt. 
The  ends  to  be  joined  should  first  be  cut  squarely 


across.  A  belt  punch  to  make  the  holes  for  the 
lacings  should  form  an  aperture  big  enough  for  the 
lacing  to  pass  freely  without  straining  the  fibre  of  the 
leather;  otherwise  there  is  a  tendency  to  tear  out,  and 


66  SCIENCE    OF   THRESHING. 

the  lacing  to  break  off.  For  ordinary  work  a  punch 
making  a  hole  about  five-sixteenths  of  an  inch  across 
is  the  most  convenient  size  for  ordinary  work.  A 
smaller  one  should  be  used  for  the  holes  for  the 
lacing  ends,  which  should  pass  through  tightly. 

In  punching  the  holes,  care  should  be  taken  to 
space  them  evenly  at  equal  distance  from  the  belt 
edge.  An  odd  number  of  holes,  as  three,  five  or 
seven,  according  to  the  width  of  the  belt,  gives  the 
best  result. 

The  start  should  be  made  by  passing  the  lacing 
ends  through  the  two  center  holes  from  the  flesh  side. 
Then  lace  from  the  center  once  through  each  hole 
until  the  belt  edge  is  reached,  using  one  end  of  the 
lacing  for  the  holes  on  one  side  of  the  center,  and  the 
other  end  for  the  other  holes  on  the  other  side  of 
the  center.  Then  pass  the  ends  of  the  lace  through 
each  outside  hole  again,  thence  through  the  suc- 
ceeding holes,  until  the  center  is  reached.  Then  pass 
the  lace  ends  up  through  the  small  retaining  holes. 
By  starting  as  described,  it  leaves  the  ends  of  the  lace 
projecting  on  the  pulley  side,  which  prevents  them 
from  slapping  and  wearing  off  as  they  pass  round  the 
pulley.  It  also  leaves  the  belt  lacings  crossed  on  the 
pulley  face  of  the  belt,  thus  giving  more  surface  for 
contact. 

When  finished  the  lacing  has  been  passed  through 
each  hole  twice,  and  is  what  is  called  double  lacing. 
The  lace  end  should  project  about  three  inches  when 
finished.  Punch  the  small  retaining  hole  in  line  with 


SCIENCE    OF    THRESHING.  67 

the  others  so  that  it  can  be  enlarged  and  used  when 
the  belt  stretches  and  is  cut  and  relaced. 

Good  lace  leather  of  uniform  width  of  about  five- 
sixteenths  of  an  inch  should  be  used,  with  the  ends 
tapered  for  convenience.  The  smooth  side  should  be 
placed  out,  as  the  lace  will  then  last  longer. 

Pulleys  are  crowned  or  larger  in  the  center  to 
cause  the  belt  to  run  in  the  center  of  the  pulley.  If 
the  shafts  of  two  pulleys  are  parallel,  the  belt  has  a 
tendency  to  run  to  the  large  part  of  the  pulleys.  If 
the  shafts  of  two  pulleys  are  nearer  together  at  one 
end,  the  belt  when  doing  work  or  is  tight,  has  a  ten- 
dency to  run  towards  the  ends  nearest  together.  If 
one  shaft  is  level  and  the  other  high  at  one  end,  the 
belt  has  a  tendency  to  run  towards  the  low  end. 
If  a  belt  slips,  it  will  run  off  on  the  side  of  the  pulleys 
nearest  together. 


CHAPTER  X. 

BABBITING  BOXES. 

With  a  little  care  and  practice,  anyone  of  ordinary 
ability  can  babbitt  boxes. 

Babbitt  metal  is  made  of  block  tin  and  antimony, 
the  best  grades  containing  a  little  copper.  Zinc 
should  not  be  used  in  babbitt  as  it  has  a  tendency  to 
cause  the  boxes  to  heat,  and  besides  does  not  wear 
long.  In  preparing  the  box  to  babbitt,  remove  any 
old  babbitt  and  clean  well,  as  any  grease  and  moisture 
would,  when  heated,  generate  gases  and  blow  the 
molten  metal  out.  Bolt  the  box  in  the  position  for 
which  it  is  intended,  as  otherwise  the  tightening  will 
throw  it  out  of  adjustment  and  line. 

Place  shimming  (pieces  of  pasteboard)  between 
the  margins  of  the  halves  of  the  box,  to  allow  an 
excess  of  metal,  to  allow  for  wear.  In  prepar- 
ing this  shimming  see  that  its  inner  edges  butt 
against  the  shaft,  in  order  to  separate  the  babbitt  in 
the  lower  half  from  the  babbitt  in  the  upper  half. 
Cut  two  or  three  small  notches,  each  about  one- 
quarter  of  an  inch  long  and  one-eighth  of  an  inch 
deep,  in  the  edges  of  the  shimming  to  allow  the  metal 
to  flow  through  into  the  lower  half  of  the  box,  the 
little  fins  thus  formed  being  readily  broken.  Hold 
the  shaft  in  place  in  the  box  by  inserting  a  leather 
strip  wrapped  around  the  shaft  at  the  box  end. 

68 


SCIENCE    OF    THRESHING.  69 

With  clay  moistened  to  the  consistency  of  stiff  dough 
seal  up  all  the  openings  thoroughly,  save  the  oil  hole. 
Plug  this  up  with  a  stick,  packing  the  clay  around  it  in 
funnel  shape,  to  pour  the  metal  in.  After  all  is  in 
readiness,  remove  the  stick  with  care  that  no  clay  falls 
into  the  hole. 

To  be  poured  successfully,  the  metal  should  be  of 
a  temperature  to  burn  wood.  To  test  it  insert  a  stick 
of  wood  occasionally  into  the  melting  pot,  and  when 
the  babbitt  makes  the  stick  smoke  or  turn  black,  it  is 
of  the  right  temperature. 

When  pouring,  the  metal  should  be  turned  in  as 
fast  as  it  will  run  through  the  opening,  to  insure  its 
filling  the  lower  half  of  the  box;  do  not  stop  until 
the  box  is  full,  as  the  metal  chills  very  quickly  and 
will  not  unite  with  fresh  metal,  after  it  has  once  set. 

After  pouring,  remove  the  clay  and  break  the  box 
apart  by  driving  a  cold  chisel  between  the  halves, 
dressing  off  the  points  of  the  broken  fins  formed  in 
the  notches  of  the  shimming.  If  the  lower  half  of 
the  box  is  not  filled,  enlarge  the  openings  in  the 
shimming  and  try  again. 

Relieve  the  shaft  by  scraping  some  of  the  babbitt 
from  the  inside  of  the  box,  removing  the  most  near 
the  inside  edges;  in  bolting  the  cap  on,  insert  an 
extra  piece  of  shimming  at  the  box  edges,  otherwise 
the  box  would  be  too  tight  if  left  as  babbitted,  and 
would  heat. 

By  inserting  a  stick  in  the  oil  hole  before  the 
metal  has  cooled,  it  will  form  an  oil  hole  and  save 
drilling  or  punching  one. 


CHAPTER  XI. 
LUBRICATION. 

The  life  of  a  machine  and  ease  of  operation 
depend  in  a  large  measure  on  the  manner  in  which 
its  journals  are  kept  lubricated. 

In  selecting  lubricants  keep  in  mind  the  purpose 
for  which  they  are  to  be  used.  In  hot,  dry  weather 
a  thicker  and  heavier  oil  can  be  used  than  in  cold 
weather.  In  places  or  bearings  subjected  to  external 
heat,  mineral  oils  are  preferable  to  those  containing 
animal  or  vegetable  matter.  There  is  a  tendency 
among  dealers  to  supply  the  cheapest  quality  of  oil, 
which  usually  proves  the  dearest  to  the  buyer. 

In  many  of  the  machine  oils  vegetable  matter 
mixed  with  kerosene  or  other  light  mineral  oil  is 
used  as  it  can  be  sold  very  cheaply.  The  kerosene 
soon  evaporates  at  the  ends  of  the  journal,  leaving 
the  vegetable  matter  in  the  box  where  it  thickens  and 
gums,  causing  the  box  to  heat  or  the  shaft  to  run 
hard.  Oil  of  this  nature  is  hard  on  paint,  where  it 
spreads  out  over  the  woodwork,  causing  the  varnish 
to  corrode  and  become  dull. 

A  good  grade  of  oil  for  general  purposes  is  what 
is  known  as  black  or  crude  oil.  It  is  a  mineral  product 
with  all  the  light  oils  removed,  and  may  be  had  of 
different  grades  of  density.  The  heavier  qualities 

70 


SCIENCE    OF    THRESHING.  71 

can  be  used  advantageously  in  warm  weather,  while 
the  lighter  grades  will  be  found  to  run  more  freely 
in  cold  weather  and  do  not  thicken  as  easily. 

Hard  oils  work  well  in  journals  when  properly 
fed.  Cylinder  oils  should  be  selected  in  view  of 
standing  a  high  temperature. 

GETTING  READY. 

If  the  machine  is  one  that  has  been  in  use  the 
previous  year,  it  should  be  inspected  carefully  and 
every  piece  put  in  proper  condition  to  maintain  a 
fall's  run,  before  the  time  announced  as  the  com- 
mencement of  the  threshing  season. 

See  that  every  box  on  the  machine  is  properly 
adjusted,  the  worn  ones  being  set  up,  and  if  much 
worn,  rebabbitted.  A  shaft  should  not  be  so  loose 
in  a  box  as  to  rattle  or  move  back  and  forth  much, 
neither  should  it  be  too  tight  to  run  easily.  The 
bearings  of  a  shaft  which  produce  or  withstand  a 
vibrating  or  oscillating  motion,  should  have  special 
attention  and  not  be  allowed  to  get  loose,  as  the  least 
play  will  permit  the  shaft  to  pound  at  each  stroke  and 
soon  wear  flat.  This  will  cause  the  vibrating  or 
oscillating  part  to  run  or  work  anything  but  smoothly, 
and  may  interfere  with  its  performing  its  proper 
work. 

The  oil  cups  should  be  gone  over  and  the  vertical 
ones  should  have  a  piece  of  waste  inserted  to  retain 
the  oil  and  keep  out  the  dirt  and  dust. 

Every  belt  should  be  properly  laced  and  stretched 


7*2  SCIENCE    OF    THRESHING. 

to  the  right  tension.  If  a  belt  is  too  tight,  it  is  much 
the  better  plan,  instead  of  overstraining  it  when 
putting  it  on,  to  let  out  the  lacing  and  then  take  it  up 
when  the  belt  has  found  its  place.  If  dry  and  hard, 
a  little  neatsfoot  oil  in  which  a  little  resin  has  been 
dissolved  will  soften  a  belt  and  add  to  its  life.  The 
rivet  heads  on  the  pulley  lagging  must  not  project 
for  they  cut  the  surface  of  the  belt  as  it  passes  over 
them. 

See  that  every  bolt  and  nut  in  the  machine  is  in  its 
proper  place  and  tightened.  If  the  frame  of  the 
machine  is  warped,  try  to  get  it  in  line.  Replace 
worn  cylinder  and  concave  teeth  with  new  ones. 
Special  attention  should  be  given  to  the  straw  rakes 
and  raddles  that  they  be  in  good  condition.  If 
wooden  trucks  are  used,  the  tires  must  be  examined  to 
see  if  they  are  tight;  if  iron  wheels  are  employed, 
every  spoke  must  be  screwed  up  to  its  proper  tension. 

The  tool  box  is  an  important  adjunct  to  a  well 
equipped  outfit.  It  should  be  •  provided  with  the 
necessary  tools,  such  as  hammers,  wrenches,  chisels, 
files,  etc.,  as  well  as  assorted  sizes  of  bolts,  screws, 
rivets  and  nails  that  are  liable  to  be  needed  at  any 
time.  Much  valuable  time  is  often  saved  by  being 
able  to  replace  such  small  parts  as  are  liable  to  be  lost 
or  broken.  Each  tool  and  article  should  have  a 
place  in  the  box  and  be  kept  there,  so  that  it  can 
be  found  when  wanted,  and  will  be  missed  from  its 
usual  position  as  soon  as  mislaid  or  lost.  The  box 
must  be  well  covered  to  exclude  all  dirt  and  chaff. 

If  the  machine  be  a  new  one,  everything  should  be 


SCIENCE  OF  THRESHING.  73 

put  in  its  proper  place  and  all  nuts  gone  over  and 
tightened.  It  is  very  good  practice  to  leave  each  nut 
standing  square  with  the  piece  on  which  it  rests; 
this  not  only  gives  the  machine  a  symmetrical  and 
workmanlike  look,  but  it  accustoms  the  eye  to  seeing 
the  nuts  stand  squarely,  so  that  it  readily  detects  any 
change  in  position  due  to  loosening,  and  thereby 
allows  of  instant  attention,  preventing  loss.  Remove 
all  cinders  and  dirt  from  the  boxes  and  running  parts 
and  pack  them  with  waste,  as  before  stated,  to 
exclude  all  foreign  substances.  Finally,  before  assem- 
bling the  crew,  run  the  machine  empty  for  a  time  to 
see  that  all  the  parts  are  properly  adjusted;  this 
gives  a  chance  also  to  adjust  the  belts,  which  when 
new,  stretch  after  being  run  a  short  time. 


CHAPTER  XII. 

THE  CREW. 

It  is  the  duty  of  the  manager  to  see  that  everything 
is  operating  properly;  look  after  the  welfare  and 
comfort  of  the  crew  and  see  that  each  performs  the 
task  assigned  him;  economize  time  and  keep  the 
expense  down  so  as  to  accomplish  the  most  work  with 
the  least  outlay;  and  in  general,  lay  out  and  plan 
the  work  so  that  there  is  no  waste  of  time  either  on 
the  part  of  the  machine  or  the  men  attending  it. 
Much  of  the  success  of  the  machine  depends  upon 
this. 

To  make  the  machine  do  its  best,  it  is  necessary  that 
each  man  should  perform  his  part;  this  should  be 
seen  to  by  the  manager  and  the  allotment  of  work 
should  be  under  his  exclusive  control.  There  is  no 
place  where  there  is  greater  necessity  for  a  head  and 
leader  than  around  a  threshing  machine.  The  man- 
ager should  assert  his  rights  in  a  firm  and  mild  man- 
ner, should  never  lose  his  temper  or  show  anger, 
should  not  abuse  any  one  or  permit  any  bullying 
among  the  crew.  It  is  very  demoralizing  to  have  a 
bully  among  the  crew,  especially  if  he  be  permitted  to 
exercise  his  inclinations  on  his  fellow  workmen.  Har- 
mony in  the  crew  rests  largely  with  the  manager,  and 
he  should  see  to  proper  adjustment  there  as  well  as  in 
the  machine  itself. 

74 


SCIENCE   OF   THRESHING.  75 

The  feeders  should  be  sufficiently  acquainted  with 
the  machine  to  be  able  to  work  in  harmony  with  it, 
in  order  that  the  work  progress  successfully.  The 
motion  and  working  of  the  machine  should  be 
watched  by  them  so  that  any  faults  may  be  corrected. 

It  is  good  practice,  and  usual  in  hand  feeding,  for 
each  to  take  his  turn,  one  feeding  a  given  time  or 
amount  of  grain,  and  then  being  relieved  by  the 
other.  The  feeder  is  the  one  who  is  depended  upon 
to  regulate  the  amount  to  be  threshed  and  the  quan- 
tity of  grain  cleaned  per  day  depends  on  him  in 
a  large  measure. 

The  feeding  should  be  even  and  continuous  and  at 
as  constant  and  steady  a  rate  as  possible  at  all  times, 
in  order  that  the  crew  may  become  accustomed  to  the 
average  amount  of  straw  and  grain  to  be  handled, 
and  so  be  able  to  judge  of  the  labor  required  of  them. 
The  motion  of  the  one  feeding  should  be  adapted  to 
the  kind  and  condition  of  the  grain  to  be  threshed. 
The  more  the  straw  is  divided  and  spread  out,  the 
less  power  will  be  consumed  in  passing  it  through  the 
cylinder.  When  the  power  is  limited,  as  in  threshing 
with  horses,  this  fact  should  be  well  borne  in  mind. 

In  steam  threshing,  where  more  grain  is  being 
handled  and  there  is  plenty  of  power,  the  feeder  has 
about  enough  to  do  to  keep  the  bundles  passing  in 
without  spending  much  time  in  spreading  them  out. 
He  should,  however,  feed  as  continuously  as  possible 
in  order  that  a  bundle  may  be  engaged  and  drawn  in 
by  the  cylinder  before  the  preceding  one  has  passed 


76  SCIENCE    OF    THRESHING. 

entirely  through.     This  aids  in  lessening  the  amount 
of  power  required. 

The  band  cutters  should  cut  the  bands  and  pass  the 
bundles  to  the  feeder  in  such  a  way  as  will  aid  him  in 
doing  his  work.  To  assist  the  free  moving  of  the 
bundles  across  the  table,  it  should  be  kept  clear  of 
clinging  straws.  Care  should  be  taken  in  the  use  of 
the  knife  used  to  cut  the  bands,  as  many  a  feeder  has 
had  his  hand  cut  by  inattention  or  carelessness  on  the 
part  of  the  band  cutter.  Each  band  cutter  should 
become  accustomed  to  one  side  of  the  machine  and 
always  work  there,  as  he  can  perform  his  work  better 
than  if  he  changes  about. 

The  pitchers  are  depended  upon  to  get  the  un- 
threshed  grain  to  the  machine  as  fast  as  needed  in  a 
way  that  will  facilitate  the  work.  There  should  be 
enough  pitchers  provided  so  that  the  machine  will 
not  have  to  wait  for  grain  or  run  partly  empty,  as  this 
will  cause  some  of  the  rest  of  the  crew  to  stand  idle 
and  will  curtail  the  earnings  of  the  machine  for  the 
day's  run. 

It  is  good  practice  for  each  man  to  keep  his  partic- 
ular position  on  one  side  of  the  machine  for  the 
entire  time  he  is  with  it.  He  thus  becomes  accus- 
tomed to  handling  the  bundles  in  a  certain  way  on 
that  side,  while  on  the  other,  the  position  and  move- 
ments are  reversed.  The  work  will  be  performed 
with  greater  expedition  and  ease  as  the  muscles 
become  accustomed  to  certain  movements. 

The  straw  crew  takes  care  of  the  straw  as  fast  as  it 
is  delivered  from  the  carrier. 


SCIENCE   OF  THRESHING.  77 

It  is  as  easy  to  form  and  build  a  good,  symmetrical 
stack,  as  to  push  the  straw  back  without  reference  to 
the  form  of  the  pile.  If  the  stack  be  commenced  well 
up  towards  the  machine  so  that  the  stacker  drops  the 
straw  near  the  center  of  the  stack;  the  straw  will  not 
have  to  be  moved  as  far  as  if  the  carrier  deposited  it 
at  the  edge  of  the  stack ;  in  the  latter  case  the  straw  or 
part  of  it,  would  have  to  be  moved  the  entire  width 
of  the  stack.  Also,  if  the  center  be  better  tramped 
than  the  edges,  the  latter  will  settle  more  so  that  the 
straw  will  incline  downward  on  the  outside,  making 
a  better  watershed;  if  the  bulk  of  the  straw  has  to 
be  moved  from  the  center  of  the  stack,  as  happens 
when  the  stacker  delivers  there,  the  straw  men  will 
naturally  stand  there,  thereby  packing  it  closely. 


CHAPTER  XIII. 
WASTING  GRAIN 

There  is  no  place  on  earth  where  a  kernel  of  grain 
looks  as  large  and  is  of  so  much  value  as  at  the  tail 
end  of  a  machine.  To  see  some  hunt  and  search  for 
them,  one  would  think  each  one  a  diamond  or  priceless 
gem.  There  is  no  time  when  a  farmer  is  so  careful 
of  his  property  as  right  then.  Any  amount  may  be 
wasted  by  the  harvester  or  in  handling  the  grain,  but 
let  him  discover  a  few  kernels  going  into  the  straw 
through  the  separator  and  he  at  once  loses  his  reason 
and  imagines  ruin  stares  him  in  the  face.  He  will 
show  them  to  the  operator  with  an  autocratic  air  of 
udo  better  or  quit." 

In  a  bushel  of  oats,  32  Ibs.,  there  are  about 
600,000  kernels.  In  a  bushel  of  wheat,  60  Ibs., 
there  are  about  1,000,000  kernels.  If  the  farmer 
should  hold  his  hand  where  the  grain  is  wasting 
fastest  for  half  a  minute,  and  should  catch  ten  kernels, 
he  would  say  that  half  of  it  was  going  in  the  straw. 
Let  us  see.  Counting  26  days  for  a  month  and 
10  hours  for  a  day,  it  would  take  him  over  three 
months  to  catch  a  bushel  of  wheat.  Oh,  yes,  he 
says,  but  he  only  held  his  hand  under  a  small 
part  of  the  falling  chaff.  Well,  suppose  the  ma- 
chine was  52  inches  wide  and  his  hand  only  two 

78 


SCIENCE   OF  THRESHING.  79 

inches,  and  the  grain  wasting  equally  across  the 
entire  width,  it  would  then  take  three  days  at  the 
same  rate  for  enough  kernels  to  pass  to  fill  a  bushel 
measure. 

In  order  to  waste  five  bushels  in  a  day  of  ten  hours' 
run,  there  would  have  to  be  138  kernels  escape  every 
second  or  8,240  every  minute.  It  is  very  deceiving 
when  the  quantity  of  grain  comes  to  be  measured  by 
the  kernel.  While  most  threshers  are  willing  to  do 
all  in  their  power  to  save  the  grain  for  their  cus- 
tomers, the  farmer  should  remember  that  absolute 
perfection  is  impossible,  and  that  the  actual  waste  is 
but  very  small  as  compared  to  the  amount  threshed. 

It  is  difficult  to  state  what  per  cent,  a  machine  may 
waste  and  still  be  doing  reasonably  good  work. 
There  have  been  several  tests  made  to  determine  this, 
but  the  conditions  varied  so  that  there  are  scarcely 
two  reports  alike.  In  ordinary  threshing,  when  the 
conditions  are  not  unfavorable  and  the  machine  is  not 
being  over  crowded,  it  should  not  waste  more  than 
one-third  of  one  per  cent;  this  will  be  only  a  little  over 
three  bushels  per  thousand.  Calling  10  hours  one  day, 
and  threshing  1,000  bushels,  to  waste  three  bushels 
would  necessitate  losing  all  which  would  lay  on 
the  palm  of  the  hand,  every  1 5  seconds,  not  a  very 
long  space  of  time,  only  a  quarter  of  a  minute.  This 
would  show  very  plain  and  the  machine  would  appear 
to  be  wasting  very  fast.  If  the  kernels  are  still  in  the 
head,  unthreshed,  the  waste  may  be  in  much  larger 
proportion;  a  kernel  in  every  head  or  two  soon 
counts  up. 


PART  II. 


TRACTION  and 

PORTABLE 

ENGINES 


INTRODUCTION. 

The  conditions  which  arise  in  the  operation  of  the 
engine  of  an  up-to-date  threshing  outfit  demand  a 
thorough  knowledge  of  the  principles  which  underlie 
its  workings. 

The  following  pages  are  designed  to  explain  the 
principles  on  which  practical  and  economical  opera- 
tions of  traction  engines  are  based. 


GENERAL  THEORY  OF  THE  GENERA- 
TION OF  STEAM 

CHAPTER  I. 
HEAT 

The  generation  of  steam  from  water  depends  upon 
the  expenditure  of  heat.  It  is  well  to  understand 
what  is  meant  by  the  term  heat. 

Heat  is  a  form  of  energy.  It  is  in  fact  a  mode  of 
motion  among  the  particles  or  molecules  which  com- 
pose matter.  If  the  molecules  are  moving  or 
vibrating  back  and  forth  among  themselves,  the 
sensation  of  heat  is  produced.  This  term  is  only 
relative ;  what  seems  cold  to  one  person  is  hot  to 
another;  but  if  we  start  from  a  common  basis  we 
may  say  that  a  high  rate  of  vibration  in  the  mole- 
cules produces  heat.  A  low  rate  produces  a  very 
much  less  degree  of  heat,  which  we  are  used  to 
calling  cold.  Inasmuch  as  any  body  in  motion  is 
capable  of  overcoming  resistance,  that  is,  doing  work, 
we  say  that  it  has  kinetic  energy;  therefore,  the  mole- 
cules which  are  vibrating  to  produce  the  effect  called 
heat  possess  this  energy,  and  hence,  we  are  right  in 
saying  that  "heat  is  a  form  of  energy." 

In  other  words,  the  molecules  of  a  heated  body 

83 


84  SCIENCE    OF    THRESHING. 

do  work  just  as  truly  as  does  a  man  who  shovels  dirt. 

The  more  heated  the  body  is,  the  faster  do  the 
molecules  vibrate,  and  the  more  work  can  they  do,  or 
the  more  energy  they  have. 

Temperature  is  a  term  used  to  denote  the  rate  of 
vibration  of  the  molecules  of  a  heated  body.  It  does 
not  express  the  quantity  of  energy  which  a  body  has, 
but  it  does  express  the  way  in  which  the  molecules  are 
vibrating.  Thus,  a  body  having  a  high  temperature 
is  said  to  be  hot ;  a  body  having  a  low  temperature  is 
said  to  be  cold.  The  temperature  of  a  small  piece 
of  iron  may  be  very  high,  yet  it  does  not  have  as 
much  heat  as  a  large  piece  which  may  be  of  the  same 
temperature. 

Bearing  these  facts  in  mind,  and  especially  that 
heat  is  but  a  form  of  energy,  or  work,  let  us  see  how 
it  is  made  to  do  work,  such  as  running  a  threshing 
machine. 

A  heated  body  may  impart  the  energy  of  its 
moving  molecules  to  an  adjacent  body,  or,  commonly 
speaking,  heat  it.  If  the  heated  fuel  in  the  boiler 
fire-box  communicates  its  heat,  its  power  to  do  work, 
its  energy,  to  the  walls  of  the  box  and  shell  of  the 
boiler,  the  latter  may  in  turn,  heat  or  energize  or 
impart  the  power  to  do  work,  to  heat  water  in  the 
boiler.  When  you  heat  water,  its  temperature  rises, 
that  is,  its  molecules  commence  to  vibrate  faster  and 
faster.  When  the  temperature  reaches  212  degrees, 
a  change  occurs  in  the  vibration  of  the  molecules. 
Their  rate  of  vibration  does  not  increase,  but  the 
length  of  vibration  increases,  the  molecules  tending 


SCIENCE   OF  THRESHING.  85 

to  move  farther  apart.  This  causes  the  body  of 
water  as  a  whole  to  expand.  Another  effect  of  heat 
is  still  further  exemplified  in  the  expansion  of  railroad 
rails  in  summer,  the  expansion  of  tires  for  setting, 
etc. 

In  other  words,  the  molecules  of  a  substance  which 
is  heated,  are  just  as  capable  of  doing  work  is  an 
able-bodied  man  armed  with  a  shovel. 

If  heat  is  applied  after  water  in  an  open  vessel 
has  reached  a  temperature  of  212  degrees,  the 
temperature  of  the  water  does  not  change,  but 
instead,  the  extra  energy  imparted  has  resulted 
in  making  the  molecules  increase  their  length  of 
vibration  as  well  as  their  rapidity.  The  molecules 
have  lost  their  power  of  inter-attraction  or  cohe- 
sion, and  are  attempting  to  fly  apart  or  expand. 
In  other  words  water  at  the  temperature  of 
212  degrees  at  atmospheric  pressure  changes  from 
a  liquid  to  a  gas,  and  this  gas,  if  allowed  to 
expand  fully,  occupies  1,700  times  the  volume 
or  space  which  the  water  did.  This  gas  is 
known  as  steam.  This  energizing  of  water  or 
putting  its  particles  or  molecules  into  motion,  this 
generating  of  steam,  is  accomplished  by  heating  it. 
As  before  said,  if  then  this  heat  has  imparted  a  power 
to  do  work,  it  is  evident  that  a  certain  amount  of  heat 
must  impart  a  certain  ability  to  overcome  resistance, 
a  certain  energy,  and  vice  versa,  the  energy  will 
produce  a  certain  amount  of  heat. 

If  the  water  is  confined  so  that  it  cannot  expand, 
as  in  a  boiler,  and  extra  heat  be  applied,  the  tempera- 


86  SCIENCE    OF    THRESHING. 

ture  will  continue  to  rise.  If  the  molecules  cannot 
increase  the  length  of  their  vibration,  they  increase  the 
number  of  vibrations.  When  heat  is  applied,  water 
either  expands  or  rises  in  temperature.  Expanded 
water  or  steam  is  of  the  same  temperature  as  the 
water  from  which  it  is  made.  It  contains  more 
energy  but  is  of  the  same  temperature. 


CHAPTER  II. 


LATENT  HEAT 

This  excess  energy — heat — which  is  used  in 
turning  the  water  into  steam  and  which  the  thermom- 
eter does  not  register  is  termed  "Latent  Heat." 
Latent  comes  from  the  Latin  word  meaning  "con- 
cealed" or  "hidden"  and  hence  is  very  appropriate. 

If  we  place  water  in  a  cylinder,  the  lower  end  of 
which  is  closed,  and  bring  a  sliding  piston  down  on 
it,  we  may  heat  the  water  to  the  212  degree  point  and 
not  see  that  any  appreciable  change  has  taken  place. 
If,  however,  we  continue  to  impart  heat  to  the  water 
the  thermometer  does  not  show  an  increase,  provided 
that  the  piston  be  not  too  heavy.  Roughly  speaking, 
as  long  as  the  piston  is  free  to  move  the  water  does 
not  rise  in  its  temperature;  that  is,  the  specific  heat 
does  not  increase,  but  the  latent  or  non-apparent  heat 
does.  As  a  result  the  energy  of  vibration  of  the 
molecules  increases  to  such  an  extent  that  the  water 
or  steam  increases  in  volume  1,700  times;  and  as  a 
consequence  the  piston  must  move  or  force  must  be 
applied  to  the  other  side  to  hold  it  in  place  against 
the  steam. 

In  other  words,  the  heat  which  has  been  given  to 
the  water,  or  the  energy,  or  work-doing  power,  has 
so  set  its  molecules  vibrating  that  their  motion  has 


88  SCIENCE    OF    THRESHING. 

become    appreciable   and  that   they   are   capable   of 
doing  work  of  a  kind  that  can  be  used. 

Now  if  the  heat  given  to  water  when  it  is  turned 
into  steam  is  capable  of  making  the  steam  do  work, 
there  must  be  a  certain  quantity  of  heat  which  will 
do  a  certain  amount  of  work.  The  standard  by 
which  we  measure  heat  is  known  as  the  British  Ther- 
mal Unit;  or,  as  commonly  abbreviated,  the  B.  T. 
U.  This  is  the  quantity  of  heat  which  is  required  to 
raise  one  pound  of  water  one  degree  in  temperature. 
Careful  experiment  has  demonstrated  that  you  must 
impart  at  least  one  B.  T.  U.  of  heat  to  water  after 
the  212  mark  is  passed  to  enable  the  steam  to  lift  one 
Ib.  in  weight  778  ft.,  or  10  Ibs.  in  weight  77.8  ft.,  or 
100  Ibs.  in  weight  7.78  ft.  In  other  words,  one  B.  T. 
U.  is  equivalent  to  778  foot-pounds,  and  you  thus 
have  the  energy  which  is  expended  by  the  vibrating, 
moving  molecules  of  the  water  to  which  heat  has 
been  applied,  measured  by  something  which  all  can 
understand,  and  which  is  the  common  term  to  denote 
the  pull  required  on  the  driving  belt  of  the  separator. 

It  has  been  found  that  the  burning  of  one  pound 
of  coal  gives  out  sufficient  heat  to  raise  the  tempera- 
ture of  14,000  Ibs.  of  water  from  62  to  63  degrees, 
or  in  the  language  of  heat,  the  coal  gives  out 
14,000  B.  T.  U.  One  B.  T.  U.  can  raise  778  Ibs. 
one  foot,  or  is  equivalent  to  778  foot-pounds.  There- 
fore, one  pound  of  coal  can  raise  14,000  X  778,  or 
10,892,000  foot-pounds;  this  amount  of  power 
would  raise  7,000  Ibs.  1,556  feet. 


UNIVERSITY 

OF  / 

SCIENCE   OF   THRESHING.  89 

The  burning  of  the  fuel  in  the  fire-box  of  the 
boiler  causes  the  molecules  of  the  fuel  to  start 
vibrating  at  a  high  rate  of  speed,  or  to  rise  to 
a  high  temperature.  This  energy  of  motion  in  the 
molecules  is  communicated  to  the  surrounding  air 
and  to  the  walls  of  the  fire-box.  Obviously  it  is 
necessary  to  see  that  as  much  of  this  energy  as  pos- 
sible be  saved  or  rather  directed  to  the  point- where  it 
can  be  used,  and  so  the  fire-box  of  the  boiler  should 
be  such  as  will  best  retain  the  heat  and  best  transmit 
it  to  the  water  in  the  boiler. 

We  have  further  seen  how  the  heat  affects  the 
water  to  which  it  is  imparted  through  the  walls  of  the 
fire-box,  and  as  a  final  step  in  our  reasoning,  we  have 
seen  how  the  vibration  of  the  molecules  of  the  water 
finally  overcomes  that  mysterious  force  which  tends 
to  hold  them  together  as  water,  and  causes  them  to  fly 
apart  or  expand.  This  power  of  expansion  we  make 
to  do  work  by  putting  something  in  the  way  of  the 
expanding  particles  which  they  must  move  before 
they  can  go  as  far  as  they  otherwise  would,  and  we" 
thus  turn  the  energy  of  the  vibrating  molecules  of  the 
burning  fuel  into  an  energy  which  we  can  harness  and 
direct  as  we  please. 

It  will  be  remembered  that  when  water  was  heated 
to  212  degrees,  the  temperature  remained  the  same, 
while  the  heat  which  was  afterwards  applied  disap- 
peared as  far  as  the  thermometer  was  concerned,  and 
this  we  called  hidden  or  latent  heat.  It  is  found  by 
careful  experiments  that  it  takes  about  144  units  of 


90  SCIENCE    OF    THRESHING. 

heat  or  B.  T.  U.  to  change  a  pound  of  ice  to  water  at 

32  degrees.  It  is  found  that  it  takes  a  quantity  of  heat 
expressed  by  about  966  B.  T.  U.  to  change  one  pound 
of  water  into  steam,  and  this,  therefore,  is  966  times 
as  much  heat  as  is  required  to  raies  a  pound  of  water 
from  62  to  63  degrees.  Thus  the  latent  heat  o  fsteam 
or  amount  of  energy  which  is  transmitted  to  steam  at 
a  temperature  of  212  degrees  is  about  966  B.  T.  U. 
At  different  temperatures,  the  latent  heat  of  steam 
differs.  The  heat  which  is  taken  into  the  water  when 
it  changes  from  water  to  steam  is  given  off  again 
when  it  condenses  or  turns  back  to  water. 


CHAPTER  III. 
COMBUSTION  OF  COAL 

When  coal  is  exposed  to  heat  in  a  furnace,  a  por- 
tion of  the  carbon  and  hydrogen,  associated  in 
various  chemical  unions  as  hydrocarbons,  are  vola- 
tilized and  passed  off.  At  a  low  temperature, 
naphthaline,  resins  and  fluids  with  high  boiling  points 
are  disengaged;  at  a  higher  temperature,  volatile 
fluids  are  disengaged;  and  at  still  higher,  olefiant 
gas,  followed  by  common  gas,  light  carburetted 
hydrogen,  which  continues  to  be  given  off  after  the 
coal  has  reached  a  low  red  heat.  What  remains  after 
the  distillatory  process  is  over,  is  coke,  which  is  the 
fixed  or  solid  carbon  of  coal,  with  earthy  matter,  the 
ash  of  the  coal. 

TABLE   NO.    I. 

Taking  the  fixed  carbon,  or  coke  remaining  in  the 
furnace  after  the  volatile  elements  are  distilled  off, 
at  60  per  cent.,  in  round  numbers,  the  following  is 
an  approximate  summary  of  the  condition  of  the 
elements  of  average  coal,  after  having  been  decom- 
posed, and  prior  to  entering  into  combustion : 

ioo  POUNDS  OF  AVERAGE  COAL  IN  THE  FURNACE 
Composition.  Lbs.  Decomposition.  Lbs. 

Carbon       Fixed     60  Fixed   Carbon    60 

Carbon       Volatilized      20  Hydrocarbons      24 

Hydrogen      5  Sulphur        1   1/4 

Sulphur      1    1/4         Water    or    Steam    9 

Oxygen      8  Nitrogen      1    1/5 

Nitrogen      1   1/5         Ash     4 

Ash      4  

100 
About     100 

91 


92 


SCIENCE    OF    THRESHING. 


This  shows  a  total  useful  combustible  of  86j4  per 
cent.,  of  which  26%  per  cent,  is  volatilized.  While 
the  decomposition  proceeds,  combustion  proceeds,  and 
the  26^4  per  cent,  of  volatilized  portions,  and  the 
60  per  cent,  of  fived  carbon,  are  successively  burned. 


TABLE   NO.    2. 


Total  heat  evolved  by  various  fuels  and  their 
equivalent  evaporative  power,  with  the  weight  of 
oxygen  and  volume  of  air  chemically  consumed. 


&*! 

„" 

S°_s 

Quantity 

of  Air 

*j      a 

3  C  3 

>    l<    01  M 

Fuel. 

a'J  * 

Consumed  per    Ib.    of 

3|f 

C    °<M    * 

—  •         c 

|s~ 

Fuel 

og    • 

•3  w  —  g 

*>     ^    JM 

^H     O  EH 

O1  r*  -H    O 

ft 

w 

Ho     i 

Lbs.              Lbs. 

Cu.  ft.       Heat  Unit.          Lbs. 

at  62°. 

Hydrogen                                  80              34  8 

457               62000               62.40 

Carbon,   making   Car- 

bonic   Acid     2.66              11.6 

152               14500               15.0 

Sulphur      1.00                4.35 

57                 4000                 4.17 

Coal,    av.     dessicated.  .  .2.45              10.7 

140               14700               15.22 

Coke,    av.    dessicated.  .  .2.49              10.81 

142               13548               14.02 

Lignite,     perfect     2.04                8.85 

116               13108               13.57 

Asphalt      2.74               11.85 

156               17040               17.64 

Wood,    dessicated     1.40                6.09 

80               10974               11.36 

Wood,    25    %   moisture.  .1.05                 4.57 

60                 7951                 8.20 

Straw,    15%%   moisture.  0.98                4.26 

56                 8144                 8.43 

Petroleum      3.29              14.33 

188               20411               21.13 

Petroleum    Oils     4.12              17.93 

235               27531               28.50 

SCIENCE   OF  THRESHING.  93 

TABLE   NO.   3. 


Silver 

1000 

Iron       

375 

Boiler   Scale 

60 

850 

Tin 

350 

Brick 

11 

Gold     

.       800 

Lead    

.       200 

Soot    

10 

The  above  table  shows  the  relative  heat  conducting 
power  of  different  substances. 

The  fact  that  soot  and  boiler  scale  are  such  poor 
heat  conductors  shows  how  essential  it  is  that  the  fire- 
box and  flues  should  be  kept  free  from  soot  and  the 
boiler  from  scale,  to  give  the  action  of  the  fire  free 
access  to  heat  the  water.  An  ordinary  threshing 
engine  will  give  from  two  to  four  horse  power  more, 
when  clean  of  soot  and  scale  than  where  dirty. 

TABLE   NO.   4. 

The  following  table  shows  the  chemical  composi- 
tion of  ordinary  firewood. 

Carbon    37.5     per   cent. 

Hydrogen     4. 5     per  cent. 

Oxygen    30.75  per   cent. 

Nitrogen     0.75   per  cent. 

Ashes     1.5     per  cent. 


75.0     per  cent. 
Hygrometric  water   25.0     per   cent. 

100.0 


94 


SCIENCE    OF   THRESHING. 


TABLE  NO.    5. 

conditions,  is  about  as  follows: 

The  composition  of  straw  in  its  ordinary  air-dried 


Wheat  Straw, 

Barley  Straw, 

Per  cent. 

Per  cent. 

Carbon     

35.86 

36.27 

Hydrogen      

5.01 

5.07 

Oxyken     

37.68 

38.26 

Nitrogen      

45 

.40 

Ashes      

5.00 

4.50 

Water    

16.00 

15.50 

100.00 


100.00 


Mean, 

Per  cent. 

36.075 

5. 
38. 

.425 
4.75 
15.75 

100.00 


TABLE    NO.    6. 


Cord    hickory    or    hard    maple   weighs  4,500    Tb .  equals   2,000  tbs.   coal. 

Cord    white   oak weighs   3,850    Ibs.  equals  1,711  Ibs.    coal. 

Cord    beech,  red  or    black  oak  weighs  3,20    fbs.  equals    1,445  Ibs.   coal, 

cord  popuar,  chestnut  or  elm   weighs  2,350    tbs.  equals  1,044  tbs.   coal. 

Cord    average    pine weighs  2,000    Ibs.  equals      890  Ibs.   coal. 

Ton    dr   y straw weighs  2,000    Tbs.  equals   1,110  Ibs.   coal. 


CHAPTER  IV. 
PROPERTIES  OF  STEAM 

If  we  heat  water  in  an  open  vessel,  it  soon  reaches 
the  temperature  of  212  degrees.  If  we  continue  to 
heat  it,  it  boils,  or  the  energy  imparted  to  its  mol- 
ecules is  such  that  their  vibrations  become  violent 
enough  to  cause  them  to  fly  off  and  thus  the  vapor  or 
steam  arises.  If  we  now  close  the  top  of  the  vessel, 
the  molecules  in  their  attempt  to  escape  encounter 
resistance  and  hence  have  to  expend  some  of  their 
energy  in  overcoming  this,  that  is,  an  extra  quantity  of 
heat  must  now  be  given  to  the  water  to  make  it  turn 
to  steam.  If  it  rests  under  the  weight  of  the  atmos- 
phere alone,  or  about  14  Ibs.  to  the  square  inch,  the 
water  will  boil  at  212  degrees.  If  the  pressure  be 
increased  to  32  Ibs.,  the  water  will  not  boil  until  it 
reaches  a  temperature  of  254  degrees.  If  the  pres- 
sure be  diminished  to  about  six  Ibs.  to  the  square  inch, 
the  boiling  point  is  about  170  degrees,  hence  the  law 
or  general  statement:  An  increase  of  pressure  on 
the  surface  of  a  liquid  raises  the  temperature  at  which 
it  boils;  a  decrease  of  pressure  lowers  the  tempera- 
ture. The  temperature  of  boiling  water  always  cor- 
responds to  its  pressure.  We  call  steam  which  is  in 
contact  with  the  surface  of  water,  saturated  steam. 
Under  the  law  just  given,  its  temperature  depends  on 
the  pressure  in  the  boiler. 

95 


CHAPTER  V. 

SATURATED  STEAM  AND  ITS 
PROPERTIES. 

Temperature  is  not  the  only  property  of  saturated 
steam  which  changes  with  the  pressure.  Other  char- 
acteristics also  change.  These  may  be  stated  briefly 
as  follows : 

i. — The  amount  of  heat  which  is  required  to  raise 
a  pound  of  water  from  32  degrees,  or  freezing,  to  the 
point  at  which  it  boils  or  steams  at  a  given  pressure. 
That  is  expressed,  of  course,  in  the  only  term  we  have 
to  measure  latent  heat,  in  B.  T.  U.,  and  is  called  the 

HEAT  OF  THE  LIQUID. 

2. — The  amount  of  heat  which  is  required  to 
change  water  at  the  temperature  at  which  it  boils  into 
steam  of  the  same  temperature.  THIS  is  CALLED 

LATENT  HEAT  OF  EVAPORIZATION,  OR  LATENT 

HEAT.     This,  too,  is  expressed  in  B.  T.  U. 

3. — The  total  amount  of  heat  required  to  change 
a  pound  of  water  at  32  degrees  to  steam  of  the 
required  temperature  and  pressure.  This  is  called 

the  TOTAL  HEAT  OF  EVAPORIZATION,  or  simply, 
TOTAL  HEAT. 

It  is  plain  that  the  TOTAL  HEAT  is  the  sum  of  the 
LATENT  HEAT  plus  the  HEAT  OF  THE  LIQUID. 

4. — The  number  of  cubic  feet  occupied  by  a  pound 


SCIENCE  OF  THRESHING.  97 

of  steam  at  the  given  pressure;  or  the  SPECIFIC 
VOLUME. 

5. — The  density  of  the  steam;  that  is,  its  weight 
per  cubic  foot  at  the  required  pressure. 

All  these  properties  may  be  collected  in  a  table  so 
as  to  be  readily  seen  and  this  is  known  to  engineers 
as  the  steam  table. 


98  SCIENCE    OF    THRESHING. 

STEAM   TABLE. 

THE  PROPERTIES  OF  SATURATED 
STEAM. 


c 

X 

Quantities  of  Heat  in  British 
Thermal  Units. 

"8 
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Volume. 

g>-< 

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70.040 

1043.015 

III3-055 

.003027 

330.4 

20623 

2 

I26.3O2 

94.368 

1026.094 

1120.462 

.005818 

171.9- 

10730 

3 

141.654 

109.764 

1015.380 

1125.144 

.008522 

"7-3 

7325 

4 

153.122 

121.271 

1007.370 

1  128.641 

.on  172 

89-51 

5588 

5 

162.370 

i30-563 

1000.899 

1131.462 

-013781 

72.56 

4530 

6 

170.173 

138.401 

995-441 

1133.842 

.016357 

61.  14 

3816 

7 

176.945 

i45-2I3 

990-695 

1135.908 

.018908 

52.89 

33°* 

8 

182.952 

1  51-255 

986.485 

1137.740 

.021436 

46.65 

2912 

9 

188.357 

156.699 

9812.690 

JI39-389 

•023944 

41-77 

2607 

10 

193.284 

161.660 

979.232 

1  140.892 

.026437 

37.83 

2361 

n 

197.814 

166.  225 

976.050 

1142.275 

.02891  r 

34-59 

2159 

12 

2O2.OI2 

170.457 

973-098 

"43-555 

.031376 

31-87 

1990 

13 

205.929 

174.402 

970.346 

1144.748 

.033828 

29.56 

1845 

209.604 

178.112 

967-757 

1  145.869 

.036265 

27-58 

1721 

14.69 

2I2.OOO 

180.531 

966.069 

1146.600 

.037928 

26.37 

1646 

15 

213.067 

181.608 

965.318 

1  146.926 

038688 

25-85 

1614 

16 

216.347 

184.919 

963.007 

1147.926 

041109 

24-33 

1519 

17 

219.452 

188.056 

960.818 

1148.874 

°435  19 

22/98 

M34 

18 

222.424 

191.058 

958.721 

1149.779 

045920 

21.78 

.  J359 

19 

225-255 

193.918 

956.725 

1  150.643 

048312 

20.70 

I  2  92 

SCIENCE  OF  THRESHING. 


99 


I 

2 

3 

4 

5 

6 

7 

8 

/ 

/ 

9 

L 

H 

w 

V 

R 

20 

227.964 

196.655 

954..8I4 

1151.469 

.050696 

19-73 

1231.0 

22 

233.069 

201.817 

951.209 

1153.026 

-055446 

18.04 

1126.0 

24 

237.803 

206.610 

947-861 

1154.471 

.060171 

16.62 

1038.0 

26 

242.225 

211.089 

944-73° 

1155.819 

.064870 

15-42 

962.3 

28 

246.376 

215.293 

941.791 

1157.084 

•069545 

14.38 

897.6 

3° 

250.293 

219.261 

939.019 

1158.280 

.074201 

13.48 

841.3 

32 

254.OO2 

223.021 

936-389 

1159.410 

.078839 

12.68 

791.8 

34 

257-523 

226.594 

933-89I 

1160.485 

.083461 

11.98 

748.0 

36 

260.883 

230.001 

931.508 

1161.509 

.088067 

11.36 

708.8 

38 

264.093 

233.261 

929.227 

1162.488 

.092657 

10.79 

673-7 

40 

267.168 

236.386 

927.040 

1163.426 

.097231 

10.28 

642.0 

42 

270.  122 

239-389 

924.940 

1164.329 

.101794 

9.826 

6l3-3 

44 

272.965 

242.275 

922.919 

1165.  194 

.106345 

9-403 

587-0 

46 

275-704 

245.061 

920.968 

1166.029 

.110884 

9.018 

563-0 

48 

278.348 

247.752 

919.084 

1166.836 

.115411 

8.665 

540.9 

50 

280.904 

250.355 

917.260 

1167.615 

.119927 

8.338 

520.5 

52 

283.381 

252-875 

9*5-494 

1168.369 

•124433 

8.037 

5°i-7 

54 

285.781 

255-321 

913.781 

1169.102 

.128928 

7-756 

484-2 

56 

288.III 

257-695 

912.118 

1169.813 

•133414 

7-496 

467.9 

58 

290.374 

260.002 

910.501 

1170.503 

.137892 

7.252 

452.7 

60 

292.575 

262:248 

908.928 

1171.  176 

142362 

7.024 

438.5 

62 

294.717 

264-433 

907.396 

1171.829 

.  146824 

6.811 

425.2 

64 

296.805 

266.566 

905.900 

1172.466 

.151277 

6.610 

412.6 

66 

298.842 

268.644 

904.443 

1173.087 

•155721 

6.422 

400.8 

68 

300.831 

270.674 

903.020 

1173.694 

.160157 

6.244 

389-8 

70 

302.774 

272.657 

901.629 

1174.286 

.164584 

6.076 

379-3 

72 

304.669 

274-597 

900.269 

U74-866 

.169003 

5-9J7 

369-4 

74 

306.526 

276.493 

898.938 

H75-431 

•173417 

5-767 

360.0 

76 

308.344 

278.350 

897-635 

1175-985 

.177825 

5.624 

351-1 

7? 

310.123 

280.  170 

896.359 

1176.529 

.  182229 

5-488 

342.6 

80 

311.866 

281.952 

895.108 

1  177.060 

.186627 

5-358 

334-5 

82 

3I3-576 

283.701 

893.879 

1177.580 

.  191017 

5-235 

326.8 

84 

3I5-25° 

285.414 

892.677 

1178.091 

.195401 

5.118 

3J9-5 

86 

316.893 

287.096 

891.496 

1178.592 

.199781 

5.006 

3I2-5 

88 

318.510 

288.750 

890-335 

1179.085 

•204155 

4.898 

305-8 

IOO 


SCIENCE    OF    THRESHING. 


I 

2 

3 

4 

5 

6 

7 

8 

p 

/ 

f 

L 

H 

w 

V 

R 

90 

32O;  O9/) 

290.373 

889.196 

1179.569 

.208525 

4-796 

299.4 

92 

32I-653 

291.970 

888.075 

1180.045 

.212892 

4.697 

293.2 

94 

323-183 

293-539 

886.972 

1180.511 

.217253 

4.603 

287.3 

96 

324.688 

295.083 

885.887 

1180.970 

.221604 

4-5*3 

281.7 

98 

326.  169 

296.601 

884.821 

1181.422 

.225950 

4.426 

276.3 

IOO 

327.625 

298.093 

883.773 

1181.866 

.230293 

4-342 

271.1 

i°5 

331-169 

301.731 

881.214 

1182.945 

.241139 

4.147 

258.9 

no 

334-582 

305.242 

878.744 

1183.986 

•251947 

3-969 

247.8 

JI5 

337-874 

308.621 

876.371 

1184.992 

.262732 

3.806 

237-6 

120 

341.058 

311.885 

874.076 

i  185.961 

.273500 

3-656 

228.3 

125 

344.136 

3I5-051 

871.848 

1186.899 

.284243 

3-518 

219.6 

130 

347-I21 

318.  121 

869.688 

1  187.809 

.294961 

3-390 

2  II'.  6 

J35 

35°-OI5 

321.105 

867.590 

1188.695 

•305659 

3.272 

204.2 

140 

352.827 

324.003 

865-552 

"89.555 

.316338 

3.161 

197.3 

*45 

355.562 

326.823 

863.567 

1190.390 

.326998 

3-058 

190.9 

15° 

358.223 

329.566 

861.634 

1191.200 

•337643 

.962 

184.9 

1  60 

363-346 

334.850 

857.912 

1192.762 

358886 

.786 

173-9 

170 

368.226 

339.892 

854.359 

1194.251 

.380071 

.631 

164.3 

1  80 

372.886 

344.708 

850.963 

1195.671 

.401201 

•493 

155.6 

190 

377-352 

349-329 

847.703 

1197.032 

.422280 

.368 

147.8 

200 

381.636 

353.766 

844-573 

1198.339 

•443310 

.256 

140.8 

2IO 

385-759 

358.041 

841.556 

II99-597 

.464295 

•154 

134.5 

220 

389-736 

362.168 

838.642 

1200.810 

•485237 

.061 

128.7 

230 

393-575 

366.152 

835.828 

1201.980 

.506139 

•976 

123.3 

240 

397-285 

370.008 

833-  103 

1203.111 

.527003 

.898 

jr8.5 

250 

400.883 

373-75° 

830.459 

1204.209 

•547831 

•  825 

114.0 

260 

404.370 

377-377 

827.896 

1205.273 

.568626 

•759 

109.8 

270 

407.755 

380.  905 

825.401 

1206.306 

•589390 

•697 

105.9 

280 

411.048 

384.337 

822.973 

1207.310 

.610124 

•639 

102.3 

290 

414.250 

387-677 

820.609 

1208.286 

.630829 

•585 

99.0 

300 

4I7-37I 

390-933 

818.305 

1209.238 

•651506 

•535 

95-8 

SCIENCE   OF   THRESHING.  IOI 

EXPLANATION  OF  THE  TABLE. 

Column  i  gives  pressures  of  from  one  to  three 
hundred  pounds.  These  are  not  gauge  pressures 
obtained  by  reading  the  gauge,  as  these  do  not  include 
the  pressure  of  the  atmosphere,  which  is  about  14.7 
Ibs.  per  square  inch.  The  gauge  is  set  to  register 
zero  when  there  is  nothing  but  the  air  pressing  on  the 
water  in  the  boiler,  and  hence  14.7  Ibs.  must  be 
added  to  all  guage  readings  to  obtain  these  ABSOLUTE 
PRESSURES. 

Column  2  gives  the  temperatures  to  which  the 
steam  rises  when  at  the  pressures  of  column  i. 

Column  3  gives  the  HEAT  OF  THE  LIQUID,  or  the 
number  of  B.  T.  U.  required  to  raise  a  pound  of 
water  from  32  degrees  to  the  boiling  point  corres- 
ponding to  the  given  pressure,  or  the  amount  of 
energy  which  goes  to  do  this  work. 

The  values  in  column  3  may  be  closely  approx- 
imated by  subtracting  32  degrees  from  the  tempera- 
ture in  column  2.  This  is  not  strictly  correct  for  all 
values,  as  the  specific  heat  of  the  water,  instead  of 
remaining  at  a  constant,  increases  slightly. 

Column  4  gives  the  LATENT  HEAT  OF  EVAPORI- 
ZATION.  This  is  the  amount  of  energy  which  is 
absorbed  in  changing  water  from  the  boiling  point 
to  steam  of  the  same  temperature  as  the  boiling 
point  of  the  water,  and  is  measured  again  in  the  very 
useful  B.  T.  U. 

Column  5  gives  the  TOTAL  HEAT  OF  EVAPORIZA- 
TION,  and  may  be  obtained  by  adding  the  corres- 
ponding values  of  columns  3  and  4. 


102  SCIENCE    OF    THRESHING. 

Column  6  gives  the  SPECIFIC  VOLUME  of  a  pound 
of  steam  at  the  given  temperature  or  pressure,  which 
is  expressed  in  pounds,  being  the  weight  of  a  cubic 
foot  of  steam  at  the  pressure  given. 

Column  7  gives  the  number  of  cubic  feet  occupied 
by  one  pound  of  steam  at  the  given  temperature,  or 

its   SPECIFIC  VOLUME. 

Column  8  gives  the  ratio  of  the  volume  of  a  pound 
of  steam  at  a  given  pressure  to  the  volume  of  a  pound 
of  water  at  the  temperature  of  39.1  degrees.  This  is 
equal  to  the  weight  of  a  cubic  foot  of  water  at  39.1 
degrees,  or  62.425  Ibs.,  divided  by  the  weight  of  a 
cubic  foot  of  steam  of  the  required  or  given  pressure, 
as  found  in  column  6. 

We  have  thus  followed  the  results  of  the  applica- 
tion of  heat  to  water  and  found  that  it  is  but  the 
taking  of  the  energy  of  an  already  heated  body,  as 
the  fuel  in  the  fire-box  of  the  boiler,  and  transmitting 
it  to  the  molecules  of  the  water,  or,  as  better 
expressed,  it  is  transmitting  the  rapid  vibrations  of 
the  molecules  of  the  fuel  to  the  molecules  of  the 
water  until  the  latter  are  moving  at  such  a  rapid  rate 
and  with  such  a  swing  that  they  overcome  cohesion, 
that  mysterious  attraction  which  particles  of  one 
kind  of  matter  have  for  each  other,  and  tend  to  fly 
apart,  or  as  we  say,  expand,  and  this  at  a  tremendous 
rate. 

By  taking  advantage  of  this  appreciable  movement 
of  the  molecules,  we  are  able  to  do  work  or  overcome 
resistance  with  them. 


CHAPTER  VI. 
THE  BOILER 

A  steam  boiler  is  an  apparatus  in  which  heat  is 
transferred  from  burning  fuel  to  water;  where  the 
energy  of  the  vibrating  molecules  of  the  burning  fuel 
is  transferred  to  the  molecules  of  the  water,  until  the 
motion  of  the  latter  becomes  so  violent  as  to  cause 
the  mass  or  volume  of  steam  to  expand  with  a  force 
which  can  be  readily  harnessed  for  use. 

A  boiler  consists  of  the  fire-box,  in  which  the 
combustion  takes  place,  the  water  space,  in  which  the 
water  is  heated  through  contact  with  a  heating  sur- 
face which  surrounds  the  fire-box,  passages  to  conduct 
away  the  smoke  and  other  products  of  combustion, 
and  various  accessories  to  furnish  water  and  regulate 
the  heat,  etc.  We  have  seen  what  a  little  loss  of  heat 
means  in  the  way  of  loss  of  energy,  or  power  to  do 
work,  and  therefore  the  fire-box  should  be  constructed 
to  direct  as  much  of  the  heat  of  the  flames  and 
burning  gases  to  the  surface  against  which  the  water 
lies  as  possible;  there  should  be  no  "dead"  corners 
where  there  is  a  loss  of  heat,  and  the  smoke  passages 
should  be  so  disposed  as  to  utilize  the  heat  from  the 
escaping  gases. 

Boilers  for  traction  engines  may  be  roughly 
divided  into  three  classes:  The  locomotive  boiler, 
the  return  flue  boiler,  and  the  vertical  or  upright 

103 


IO4  SCIENCE    OF    THRESHING. 

boiler.  The  locomotive  boiler  is  so  called  from  its 
resemblance  to  the  type  used  in  locomotive  practice. 

Its  parts  are,  first,  a  rectangular  fire-box,  a,  held  in 
position  in  the  shell  of  the  boiler  by  stay  bolts,  c. 

Second,  the  waist,  a  cylindrical  portion,  d,  through 
which  pass  the  tubes  or  flues,  e,  connecting  the  fire- 
box with  the  smoke  box,  /. 

Third,  the  steam  dome,  gt  from  which  the  steam 
may  be  taken. 


ILLUSTRATION  IN  SECTION  OF  BOILER. 

The  flat  portions  of  the  boiler  above  the  fire  door 
and  over  the  front  ends  of  the  flues  are  stayed  by 
long  rods  called  stay  rods.  The  crown  sheet  over 
the  fire-box  is  supported  by  stay  bolts. 

In  a  return  flue  boiler,  the  fire  box  extends  the 
whole  length  of  the  boiler,  which  is  usually  tubular, 
and  the  flues  come  back  through  the  shell  returning 
the  smoke  to  the  fire  door  end. 


SCIENCE   OF  THRESHING. 


105 


The  vertical  type  comprises  merely  a  vertical, 
cylindrical  shell  with  vertical  flues  and  fire-box  under 
them. 

The  main  object  in  the  distribution  and  arrange- 
ment of  the  parts  are  twofold.  First,  direction  of  the 
heat  of  the  fuel  against  spaces  or  walls  the  other  side 
of  which  are  in  contact  with  the  water,  so  that  the 
energy  of  the  burning  fuel  may  not  be  dissipated  or 
wasted  on  the  outer  air,  or  outer  parts  of  the  boiler. 
Second,  presenting  as  large  a  surface  of  water  as 
possible  to  the  heated  surfaces.  The  fire-box  should 
be  arranged  with  proper  grates  and  draft  openings 
to  suit  the  fuel  to  be  used  and  should  be  easily 
cleaned.  The  water  spaces  should  surround  the  fire- 
box as  completely  as  possible  so  as  to  present  a  large 
heating  surface  and  prevent  its  plates  from  over- 
heating. The  boiler  should  be  cleaned  regularly  of 
all  mud  and  settlings  left  by  boiling  away  the  water. 
When  using  ordinary  well  water,  once  a  week  is  often 
enough  to  clean  out.  In  muddy  or  alkali  water,  the 
boiler  may  require  to  be  emptied  oftener  than  once 
a  week. 


CHAPTER  VII. 
BOILER  FEEDERS. 

ATMOSPHERIC   PRESSURE. 

The  atmosphere  or  air  surrounding  the  earth  has 
a  weight  or  pressure  on  the  surface  of  the  earth  of 
about  15  Ibs.  per  square  inch.  This  pressure  varies 
at  different  heights.  Three  and  one-half  miles  up 
the  pressure  is  only  one-half  that  at  the  surface. 
Down  in  the  mines  the  pressure  is  greater  than  at  the 
surface.  The  pressure  is  everywhere  pressing  on  all 
objects  on  their  lower  sides  as  well  as  on  their  upper 
sides  and  has  a  tendency  to  fill  all  space.  Air  is 
elastic  and  when  relieved  of  its  pressure  it  will  expand; 
when  under  pressure  it  will  contract  and  occupy  less 
space;  at  one-half  the  pressure  it  will  occupy  twice 
the  space;  at  twice  the  pressure  it  occupies  one-half 
the  space. 

As  the  water  in  the  boiler  evaporates  or  passes  off 
in  steam,  it  must  be  replaced,  and  this  is  done  by 
devices  adapted  to  force  water  into  the  boiler.  There 
are  two  general  kinds  of  boiler  feeders  in  common 
use,  pumps  and  injectors. 

PUMPS. 

Pumps  are  either  self  acting,  (independent),  or 
else  they  are  operated  by  the  piston  or  crosshead  of 
the  engine,  hence  called  crosshead  pumps.  Their 

106 


SCIENCE  OF  THRESHING. 


107 


main  features  do  not  otherwise  differ.  The  essen- 
tial parts  consist  of  a  barrel  in  which  a  plunger  works, 
an  inlet  valve  to  the  barrel,  and  an  outlet  valve. 


The  plunger  must  have  an  air  tight  packing  around 
it  at  the  end  of  the  barrel  which  it  enters,  to  exclude 
the  air,  so  that  when  it  is  drawn  out,  the  attempt  of 
the  outer  air  to  get  in  will  force  the  water  in  through 
the  inlet  valve.  When  the  plunger  is  forced  back  in, 
the  water  is  pushed  out  through  the  outlet  valve 
which  permits  its  escape  but  closes  against  its  return. 
The  figure  shows  a  pump  having  a  piston,  A,  barrel, 
B,  inlet  valve,  C,  and  outlet  valve,  D.  There  is  an 
air  chamber,  E,  opening  into  the  pipe  beyond  the 
outlet  valve,  so  as  to  relieve  anv  undue  sudden  pres- 


I08  SCIENCE    OF    THRESHING. 

sure  in  the  pipe,  while  a  check  valve,  F,  beyond  the 
chamber  prevents  any  back  pressure  from  the  boiler. 
A  very  essential  feature  of  the  pump  is  an  air  relief 
cock,  G,  by  which  the  air  ahead  of  the  piston  and  in 
the  passages  of  the  pump  can  be  allowed  to  escape 
when  the  pump  is  first  started,  the  cock  being  kept 
open  until  water  passes  out  of  it. 

When  the  piston,  A,  is  forced  ahead  into  the  bar- 
rel, Ey  it  pushes  the  water  in  the  barrel  out  through 
the  outlet  valve,  D.  At  each  stroke  of  the  pump,  the 
barrel  is  alternately  filled  and  emptied,  thus  imparting 
an  intermittent  motion  to  the  column  of  water  going 
into  the  boiler.  To  partially  overcome  this  starting 
and  stopping  of  the  water  so  suddenly  and  frequently, 
an  air  chamber,  E,  communicating  with  the  feed  pipe 
is  placed  between  the  pump  and  the  boiler.  When 
the  water  is  suddenly  forced  out  of  the  pump  by  the 
plunger,  a  part  of  it  enters  the  air  chamber,  com- 
pressing the  air;  when  the  plunger  reaches  the  end  of 
its  stroke  and  ceases  to  force  the  water,  the  air  in  the 
air  chamber  expands  and  causes  the  water  to  continue 
to  flow  into  the  boiler  after  the  valve,  D,  has  closed, 
thus  lengthening  the  pulsations  of  the  water  and 
acting  as  a  spring  or  cushion  for  the  water  column. 
Care  should  be  taken  that  the  air  chamber  is  tight  so 
that  the  air  cannot  leak  out  and  spoil  the  cushioning 
of  the  water,  as  it  is  hard  on  valves,  packing  and 
joints  of  the  pump  if  the  plunger  is  obliged  to  set  the 
whole  column  of  water  from  the  pump  to  the  boiler 
into  motion  as  suddenly  as  it  would  do  if  the  air 
cushion  were  not  there. 


SCIENCE    OF   THRESHING  109 

Sometimes  high  speed  pumps  with  long  inlet  pipes 
work  better  with  an  air  chamber  just  outside  the 
inlet  valve,  communicating  with  the  inlet  pipe  to  give 
the  column  of  water  flowing  into  the  pump  a  more 
uniform  motion. 

If  there  is  any  air  admitted  to  the  pump  it  expands, 
and  reduces  the  vacuum  caused  by  the  withdrawal  of 
the  piston,  thereby  diminishing  the  pressure  of  the 
outer  air  on  the  water  at  the  feed  pipe  mouth,  and  to 
that  extent  impeding  the  inflow  of  water.  If  the 
water  is  too  hot,  so  as  to  steam,  the  vapor  fills  the 
cylinder  instead  of  the  fluid,  and  so  interferes  with 
its  working. 

INJECTORS. 

Injectors  make  use  of  a  jet  of  steam  to  force  the 
feed  water  into  the  boiler.  Although  there  are 
many  makes  and  kinds,  they  all  work  on  the  same 
general  plan. 

The  injector  consists  in  general  of  a  suction 
chamber,  a  condensing  tube,  and  an  overflow  valve. 
Live  steam  is  taken  from  the  boiler  directly  through 
a  pipe  to  the  injector.  As  it  is  forced  through  the 
condensing  tube,  it  forms  a  vacuum  therein  so 
that  the  water  is  lifted  and  enters  the  condensing 
tube,  intermingling  with  the  steam.  The  water 
being  cold,  this  condenses  the  steam  and  greatly  re- 
duces its  bulk,  so  that  the  combined  columns  of  water 
and  steam,  as  thus  condensed,  are  smaller  than  the 
column  of  steam  alone  as  it  comes  from  the  boiler; 
so  there  is  a  less  volume  or  bulk  of  water  entering 


110  SCIENCE  OF  THRESHING. 

the  boiler  than  there  is  leaving  it  in  the  form  of 
steam.  The  resulting  unbalanced  pressure  thus  keeps 
up  the  circulation  and  the  injector  works  contin- 
uously. 

All  joints  should  be  kept  tight  to  prevent  air  from 
entering  the  injector;  as  air  does  not  condense 
like  steam  it  would  prevent  the  injector  from  working 
properly. 


CHAPTER  VIII. 
BOILER  PARTS. 

FUSIBLE  PLUGS. 

A  very  necessary  adjunct  to  the  boiler,  especially 
in  the  case  of  traction  engines,  is  the  fusible  plug, 
which  is  placed  in  the  crown  sheet  to  give  notice  of 
low  water.  The  plug  consists  of  a  brass  bushing  filled 
with  an  alloy  of  tin,  lead,  and  bismuth  which  melts 
at  a  low  temperature.  So  long  as  the  furnace  crown 
is  kept  well  covered  with  water,  its  comparatively  low 
temperature  prevents  the  plug  from  melting  and  it 
remains  intact.  But  the  moment  that  the  water  gets 
low  enough  to  uncover  the  top  of  the  plug,  it  melts 
quickly  and  the  combined  water  and  steam  from  the 
boiler  rushes  down  on  the  fire  and  so  reduces  the  heat 
before  the  crown  sheet  is  damaged.  This  fusible 
plug  of  alloy  is  inserted  in  a  bushing  which  is  screwed 
home  in  a  hole  in  the  crown  sheet. 

GRATES. 

The  ordinary  type  of  furnace  grate  is  made  of  cast 
iron  bars  which  are  placed  side  by  side  in  the  furnace. 
The  thickness  of  the  lugs  cast  on  the  sides  of  the 
bars  determines  the  width  of  the  air  spaces  between 
the  bars.  These  spaces  admit  air  to  the  bed  of  fuel; 
consequently  the  width  of  the  spaces  depends  upon 
the  fuel  to  be  burned  and  the  amount  of  air  it  needs. 

in 


112  SCIENCE   OF   THRESHING. 

For  anthracite  coal  the  spaces  should  be  from  three- 
eighths  of  an  inch  to  half  an  inch  wide;  while  for 
coals  that  cake  much,  the  width  of  the  spaces  may  be 
from  five-eighths  to  three- fourths  inches.  For  wood 
or  straw  the  spaces  must  be  still  wider.  The  bars  are 
about  three-fourths  inches  wide  at  the  top  and  taper 
toward  the  bottom. 

SAFETY  VALVE. 

A  safety  valve  is  attached  to  a  boiler  to  prevent  the 
steam  from  rising  above  working  pressure.  When 
steam  is  generated  more  rapidly  than  it  is  used,  its 
pressure  must  of  necessity  rise,  and  if  no  means  of 
escape  are  afforded  it,  the  result  must  be  an  explosion. 

The  ordinary  form  of  valve  used  on  traction 
engines  merely  comprises  a  circular  plug  or  closure 
held  to  its  seat  against  the  outward  thrust  of  the 
steam  pressure  by  a  suitably  disposed  spring.  There 
are  many  different  forms,  but  they  all  amount  to  the 
same  thing,  differing  only  in  their  minor  details. 

The  area  of  the  valve  is  the  area  of  the  opening  in 
the  valve  seat  on  which  the  spring  pressed  valve  plug 
rests,  or  is  the  projected  area  of  the  valve  plug  sur- 
face which  is  in  direct  contact  with  the  steam  when 
the  valve  is  closed.  The  area  should  be  large  enough 
to  discharge  the  steam  as  fast  as  the  boiler  will 
generate  it,  as  otherwise  the  pressure  will  rise  even 
when  the  valve  is  open.  The  following  rule  is  a  safe 
one  to  follow  in  computing  the  area  necessary  for 
the  boiler: 

Divide  one-half  of  the  number  of  pounds  of  steam 
generated  per  hour  by  the  blow-off  pressure  increased 


SCIENCE   OF  THRESHING.  113 

by  10 ;    the  result  will  be  the  valve  area  in  square 
inches. 

The  safety  valve  should  be  placed  in  direct  connec- 
tion with  the  boiler  so  that  there  is  no  possible  chance 
of  cutting  off  the  communication  between  them. 

THE    STEAM    GAUGE. 

The  steam  gauge  indicates  the  pounds  pressure  of 
the  steam  in  the  boiler.  The  article  is  too  well  known 
to  need  special  mention. 

So  far  there  have  been  described  the  device  in 
which  the  steam  is  generated  and  a  few  of  the  acces- 
sories by  which  note  is  kept  of  the  condition  of  the 
steam  and  water  in  its  interior.  It  must  not  be  lost 
sight  of  that  the  boiler  and  its  fire-box  are  but  a  means 
to  transfer  the  latent  heat,  that  is,  the  rapid  vibrations 
of  the  molecules  of  the  burning  fuel,  to  the  mole- 
cules of  the  water  in  the  boiler,  which  tend  to  cause 
the  latter  to  fly  apart  and  thereby  impart  motion  to 
an  engine  piston.  Remembering  this  fact,  and  that 
it  means  dollars  in  the  pocket  of  the  engine  owner 
to  have  as  many  of  these  foot-pounds  of  energy  trans- 
ferred without  loss  as  is  possible,  it  is  well  to  heed  the 
following  hints. 


CHAPTER  IX. 

CARE  OF  THE  BOILER. 

The  boiler  should  be  examined  carefully  to  see  that 
all  the  plates  exposed  to  the  fire  are  free  from  heavy 
scale  and  not  banked  with  dirt  and  mud.  If  the 
boiler  be  an  old  one,  stay  bolts  and  flat  surfaces 
should  be  examined  for  breaks  and  ruptures,  and  the 
shell  should  be  tested  for  thin  places  caused  by  the 
rusting  of  the  metal,  by  pounding  with  a  hammer. 
Thin  places  easily  dent  under  the  hammer  blows,  and 
if  they  extend  over  a  large  section  of  the  boiler  it  is 
unsafe  to  run  even  at  a  very  low  pressure. 

The  position  of  the  gauge  glass  should  be 
determined  so  that  the  engineer  may  know  how  much 
water  there  is  on  the  crown  sheet  when  the  gauge 
shows  an  inch  or  more.  This  is  easily  done  by 
removing  the  hand  hole  plate  at  the  rear  of  the  boiler 
after  the  engine  is  in  a  level  position.  Then  open 
the  valves  leading  to  the  gauge  glass  and  fill  the 
boiler  with  water  until  the  crown  sheet,  which  may 
be  readily  seen,  is  covered  with  the  depth  of  water 
required;  this  may  be  from  two  to  five  inches, 
according  to  the  arrangement  of  the  steam  and  water 
space.  By  noting  the  depth  registered  in  the  gauge 
glass  when  the  desired  depth  is  obtained,  the  engineer 
will  have  means  of  knowing  just  how  much  water 

114 


SCIENCE  OF  THRESHING.  115 

there  is  in  his  boiler.  The  position  of  the  engine  must 
be  taken  into  consideration  also,  as  he  will  carry  a 
greater  depth  when  the  engine  is  tilted  back,  so 
causing  the  water  to  run  up  in  the  gauge,  to  insure 
that  the  forward  or  upper  end  of  the  crown  sheet  be 
covered.  Conversely,  if  the  engine  be  tilted  forward, 
he  will  carry  less,  as  the  gauge  glass  will  be  at  the 
higher  end  of  the  crown  sheet.  If  the  engine  be 
tipped  sideways,  this  must  also  be  taken  into  account 
to  prevent  a  burned  fire-  sheet.  If  the  engine  be  trav- 
eling along  the  road,  good  watch  will  have  to  be  kept, 
as  it  is  difficult  to  tell,  from  the  agitation  of  the 
water,  just  how  much  there  is.  In  running  down  a 
steep  hill,  the  water  is  liable  to  run  forward  in  the 
boiler  and  leave  the  crown  sheet  bare.  Therefore, 
before  reaching  the  crest  of  the  hill,  the  boiler  should 
be  filled  enough  to  insure  the  covering  of  the  crown 
sheet;  the  fire  may  also  be  deadened  for  a  time  by 
putting  on  a  layer  of  fresh  coal. 

When  steaming  up,  the  boiler  should  be  properly 
filled  and  a  fire  started  in  the  fire-box  with  all  the 
drafts  open  and  the  spark  arrester  removed  from  the 
stack,  when  possible,  as  it  impedes  the  draft.  When 
using  natural  draft  only,  the  fuel  on  the  grate  should 
be  as  thin  as  possible. 

When  steam  commences  to  rise,  the  steam  gauge 
should  be  watched  closely  to  see  if  the  hand  com- 
mences to  move  and  indicate  the  pressure.  If  it  stays 
stationary  until  a  pressure  of  five  to  ten  pounds  is 
obtained,  it  should  be  removed  and.  tested,  as  it  is 
inaccurate  and  not  to  be  relied  on. 


Il6  SCIENCE   OF  THRESHING. 

When  the  steam  gauge  registers  fifteen  or  twenty 
pounds,  the  blower  may  be  opened,  but  this  should  be 
done  with  caution,  as  the  fierce  heat  resulting  from 
its  use  is  very  trying  on  the  parts  directly  exposed  to 
the  fire.  The  heat  too  will  be  unequally  distributed 
in  different  parts  of  the  boiler  and  the  result  will  be 
unequal  expansion  and  consequent  leakage  and  weak- 
ening of  joints.  The  initial  or  first  firing  of  the 
boiler  should  be  done  with  care,  in  order  to  bring  all 
the  parts  to  as  even  a  heat  as  possible.  The  average 
sized  traction  boiler  should  be  allowed  from  forty- 
five  minutes  to  an  hour  in  which  to  come  to  a  full 
head  of  steam. 

Soot  and  scale  are  very  poor  conductors  of  heat, 
and  the  fire  walls  and  flues  should  be  kept  as  free 
from  them  as  possible  in  order  that  they  may  have  a 
fair  chance  to  transmit  the  heat  as  directly  as  possible 
to  the  water.  The  losses  consequent  on  leaving  the 
firewalls  lined  with  dirt  amount  to  a  considerable, 
from  the  extra  amount  of  fuel  required  to  generate 
the  heat. 

The  boiler  should  not  be  blown  off  when  hot,  as  the 
sudden  cooling  is  as  bad  as  the  sudden  heating,  while 
any  scale  on  the  shell  and  flues  hardens  and  bakes  on 
the  walls,  thereby  being  removed  with  difficulty. 

The  boiler  should  be  properly  jacketed  with  a 
covering  of  non-conducting  material  to  prevent  loss 
of  heat  by  radiation. 

Inasmuch  as  the  traction  engine  uses  all  kinds  of 
water,  some  highly  alkaline  or  soapy,  thereby 
foaming,  and  others  highly  acid,  corroding  the  plates, 


SCIENCE   OF   THRESHING.  I  17 

the    boiler    should    be    cleaned    frequently    and    all 
deposits  removed. 

When  boilers  are  worked  to  their  fullest  capacity, 
and  the  engine  makes  a  sudden  demand  for  more 
steam,  the  reducing  of  the  pressure  will  suddenly 
liberate  a  large  quantity  of  steam,  and  the  violent 
effort  this  makes  to  escape  from  the  surface  of  the 
water,  will  cause  increased  foaming  and  priming.  In 
case  the  increased  roaring  in  the  exhaust  gives 
warning  of  this,  the  throttle  may  be  closed  momen- 
tarily, and  then  opened  again  gradually,  without 
allowing  the  engine  to  lose  much  headway. 


CHAPTER  X. 

FIRING. 

The  fire  should  be  kept  as  regular  as  possible, 
and  this  may  readily  be  done  by  placing  the  fuel  on 
the  grate  in  such  a  manner  as  to  insure  an  even  fire. 
This  may  be  conveniently  done  in  the  following  man- 
ner: 

Shovel  regularly  as  possible  to  the  fire-box. 

First,  shovelful  at  left  hand,  back  corner;  close 
door  and  wait. 

Second,  shovelful  at  right  hand,  back  corner ;  close 
door  and  wait. 

Third,  shovelful  at  right  hand,  front  corner;  close 
door  and  wait. 

Fourth,  shovelful  at  left  hand,  front  corner;  close 
door  and  wait. 

Fifth,  shovelful  at  right  hand,  center  of  box;  close 
door  and  wait. 

Sixth,  shovelful  at  left  hand,  center  of  box;  close 
door  and  wait. 

And  repeat  in  same  order.  Wait  the  same  time 
between  each  shovelful,  so  that  there  is  uniform, 
regular  adding  of  fresh  fuel. 

A  thin  fire  on  the  grate  is  more  economical  than  a 
thick  one,  as  it  permits  the  air  to  come  in  contact  with 
each  part  of  the  burning  coal  better  than  if  the  fuel 
is  laid  deep  on  the  grate.  With  a  little  care  in 

xx8 


SCIENCE   OF   THRESHING.  119 

watching  the  fire  bed  and  allowing  no  places  on  the 
grate  to  be  bare  of  burning  coal  and  no  part  so 
loaded  as  to  prevent  air  from  passing  up  through  the 
grate  freely,  a  fierce  and  hot  fire  can  be  maintained 
with  a  minimum  expenditure  of  coal. 

The  ashes  below  the  grates  should  be  kept  cleared 
away  and  the  spaces  between  the  grates  open  to  allow 
free  passage  of  the  air. 

Oftentimes  the  water  used  deposits  lime  or  like 
substances  on  the  inside  of  the  shell.  These  cake 
over  the  heating  surface,  and  as  they  are  not  ready 
conductors  of  heat,  the  boiler  will  require  more  fuel 
than  it  should  in  order  to  generate  steam  enough. 
Consequently,  if  the  engineer  finds  that  an  engine  is 
not  supplying  power  enough,  he  should  first  find  If 
the  boiler  and  its  smoke  passages  are  in  proper  order. 
In  the  narrow  spaces  between  the  side  plates  of  the 
fire-box  and  outer  shell,  scale  sometimes  accumulates 
to  such  an  extent  as  to  completely  fill  the  interval 
between  the  plates.  The  energy  of  the  molecules  of 
the  burning  fuel  is  largely  expended  in  heating  this 
scale  and  as  a  consequence  the  water  is  not  turned  to 
steam  rapidly  enough. 

In  order  to  keep  the  parts  in  direct  contact  with  the 
fire  from  burning  out  or  leaking,  the  water  must  be 
kept  in  the  boiler  at  a  level  which  will  cover  them. 
The  engineer  is  aided  in  this  by  the  familiar  water 
glass,  also  by  a  row  of  gauge  cocks  placed  one  above 
the  other.  By  opening  these  the  depth  of  the  water 
can  be  readily  determined. 

In  a  traction  engine,  such  as  used  with  a  threshing 


120  SCIENCE   OF   THRESHING. 

outfit  the  boiler  not  only  has  to  maintain  its  form 
against  internal  stress,  but  it  performs  the  office  of  a 
frame  on  which  the  engine  is  mounted,  therefore  it 
must  be  strong  to  withstand  this  strain  as  well  as  the 
steam  pressure. 


CHAPTER  XL 

THE  MECHANISM  OF  THE  STEAM 
ENGINE. 

In  the  theory  of  the  generation  of  steam  it  will  be 
remembered  that  the  heat  of  the  burning  fuel  was  but 
the  motion  (vibrations)  of  its  molecules;  that  if  this 
motion  was  transferred  to  the  water  in  the  boiler 
(through  contact  with  the  sheet  and  flues)  it  absorbs 
a  portion  of  the  heat,  that  is,  its  molecules  commence 
to  vibrate  rapidly  until  the  boiling  point  is  reached, 
at  which  point  it  fails  to  increase  in  temperature 
though  the  fire  continues  to  burn.  This  was  because 
a  portion  of  it,  the  heat,  the  energy,  the  work-doing 
power  of  the  molecules,  was  transferred  into  giving  a 
longer  swing  to  the  molecules  of  the  water  until  they 
lost  their  power  of  staying  together  (their  cohesion), 
and  separated,  forming  an  elastic,  expanding  gas 
called  steam.  The  engine  is  but  an  instrument  for 
transmitting  the  motion  of  expanding  particles  of 
steam  into  a  regular,  constant  movement  which  may 
be  made  to  do  work,  and  the  better  the  parts  are 
arranged  and  adjusted  with  this  in  view,  the  more 
and  better  work  it  will  do. 

THE   CYLINDER. 

The  usual  method  of  obtaining  work  from  heat  is 
to  admit  the  steam  from  a  boiler,  where  it  has  been 

121 


122  SCIENCE   OF  THRESHING. 

generated  at  high  pressure,  into  one  end  of  a  cylinder 
fitted  with  a  piston.  The  end  into  which  the  steam  is 
admitted  is  open  to  the  entrance  of  the  steam  from 
the  boiler  and  the  other  end  is  open  to  the  atmosphere 
(in  the  simple  engine),  so  that  the  piston  may  move 
freely  in  that  direction.  The  pressure  of  the  steam 
from  the  boiler  drives  the  piston  to  the  opened  end 
of  the  cylinder.  When  the  piston  has  reached  that 
end  of  the  cylinder,  that  end  is  put  in  communication 
with  the  boiler  and  the  other  end  is  opened  to  the  air, 
and  the  piston  returns,  driving  the  used  steam  out 
before  it.  When  the  piston  is  at  that  end  of  the 
stroke,  the  operation  is  repeated  and  the  piston  is  thus 
made  to  move  back  and  forth  indefinitely. 

The  piston  moves  to  the  right  or  the  left  because 
the  work  doing  properties  of  the  steam  behind  the 
piston  are  greater  than  are  those  of  the  expanded  or 
partially  expanded  steam,  or  exhaust  steam.  This 
means  that  the  vibrations  of  the  molecules  of  steam 
on  the  boiler  or  pressure  side  of  the  piston  are  greater 
than  those  on  the  other,  or  exhaust  side.  The 
molecules  of  the  former  are  moving  faster  than  the 
molecules  of  the  latter  and  thus  the  difference  between 
the  energy  of  the  former  and  that  of  the  latter  is  just 
equal  to  doing  the  work  of  moving  the  piston. 

It  is  necessary  to  change  the  to-and-fro  motion  of 
the  piston  to  a  continuous  rotary  motion  in  one  direc- 
tion. The  usual  form  of  mechanism  for  accom- 
plishing this  is  known  to  engine  men  as  the  crank 
motion. 


SCIENCE   OF   THRESHING. 


I23 


A  represents  the  cylinder  provided  with  a  piston, 
B,  while  C  is  the  piston  rod.  A  link  or  connecting 
rod,  D,  is  jointed  or  pivoted  to  the  end  of  another 
link  or  crank  arm,  E,  the  other  end  of  the  latter 
being  rigidly  secured  to  a  shaft,  F,  which  revolves 
in  fixed  bearings.  When  the  piston,  B,  is  at  the  end 
of  the  cylinder  farthest  from  the  crank  or  con- 
necting rod,  which  is  commonly  called  the  head  end 
of  the  cylinder,  the  piston  rod,  C}  connecting  rod  D 
and  crank  E  are  all  in  the  same  straight  line.  As  the 
piston  returns  to  the  other  end  of  the  cylinder,  the 
crank  arm  is  caused  to  revolve  about  the  end  fixed 
to  the  shaft  and  so  imparts  a  continuous  motion  to 
the  latter.  The  parts  which  move  back  and  forth  are 
called  the  reciprocating  parts.  The  outer  end  of  the 
cylinder  or  head  is  called  the  outboard  or  cylinder 
end;  the  other  end  is  called  the  inboard  or  crank  end. 
If  the  crank  moves  in  the  direction  indicated  by  the 
arrow  it  is  said  to  run  over.  If  it  moves  in  the  other 
way  it  is  said  to  run  under.  H  is  the  head  end  and  G 
the  crank  end  of  the  cylinder;  N  andNi  are  the  cyl- 


124  SCIENCE   OF.  THRESHING. 

inder  heads,  through  the  latter  of  which  runs  or  slides 
the  piston  stem  or  rod.  Steam  is  prevented  from 
escaping  around  the  rod  by  means  of  a  stuffing  box, 
K,  in  which  expansive  packing  is  placed  and  secured 
by  the  stuffing  box  head.  The  piston  rod  is  connected 
at  its  inner  end  to  the  piston  head  which  slides  loosely 
in  the  cylinder,  and  is  provided  with  expansion 
packing  rings,  M,  which  spring  out  and  bear  evenly 
around  against  the  cylinder  wall  and  so  make  a 
steam  tight  joint. 

Steam  is  admitted  to  the  cylinder  through  a  supply 
pipe,  S,  which  enters  a  steam  chest,  O;  from  thence 
it  passes  through  steam  ports,  Pt  which  conduct  it  to 
each  end  of  the  cylinder.  The  ports  are  formed  in  a 
valve  seat,  Q,  on  which  a  slide  valve,  T,  moves  back- 
ward and  forward  through  the  agency  of  the  valve 
stem,  R,  which  passes  out  of  the  steam  chest  through 
a  stuffing  box  similar  to  the  piston  stem  box  and  is 
operated  by  an  eccentric  on  the  main  shaft. 

The  valve  is  so  arranged  as  to  simultaneously 
cover  in  one  position  one  of  the  steam  ports  and  an 
exhaust  port,  U.  There  is  a  steam  passage  through 
the  under  side  of  the  valve,  so  that  when  the  ports 
are  so  connected,  the  exhaust  steam  can  escape  under 
the  valve  through  the  exhaust  pipe.  Only  one  steam 
port  is  open  at  a  time,  and  this  enables  the  steam  to 
get  in  behind  the  piston  and  drive  it  forward;  mean- 
time the  valve  is  shifting,  so  that  the  steam  is  soon 
cut  off  and  as  the  piston  reaches  the  end  of  its  stroke, 
the  opposite  port  is  uncovered  and  the  steam  again 
enters  behind  the  piston  at  the  other  end.  In  the 


SCIENCE   OF   THRESHING.  125 

figure  the  port  to  the  left  is  being  closed  while  that 
to  the  right  is  in  communication  with  the  exhaust 
port.  After  the  left  port  is  entirely  closed  the  piston 
will  be  driven  to  the  end  of  its  stroke  by  the  expan- 
sion of  the  steam  already  admitted. 

It  will  be  seen  that  it  is  necessary  to  keep  the  valve 
seat  and  face  of  the  valve  true,  so  that  the  steam  may 
not  leak  through  and  thus  cause  a  waste.  In  any 
form  of  valve  used  (the  one  shown  is  the  common 
slide),  it  is  necessary  that  the  valve  either  move  on 
or  seat  itself  on  the  seat  accurately  so  as  to  prevent 
loss  of  power. 

In  case  a  slide  valve  is  used,  fashioned  as  that  illus- 
trated, there  is  a  heavy  pressure  of  steam  on  its  upper 
surface.  This  pressure  is  often  lessened  by  the  shaping 
of  the  valve  so  that  the  steam  bears  on  parts  of  the 
valve  which  are  on  the  opposite  side  to  the  parts 
above  the  ports.  This,  of  course,  balances  in  part 
the  pressure,  as  only  that  part  of  the  valve  above  the 
port  which  it  is  covering  and  the  surrounding  valve 
seat  is  not  sustained  by  an  equal  and  opposite 
pressure.  These  forms  of  valve  are  called  "balanced 
valves."  In  any  type  of  valve  it  is  necessary  to  lubri- 
cate well,  and  this  is  conveniently  done  by  feeding  in  a 
continuous  supply  of  oil  to  the  steam  as  it  enters  the 
steam  chest  from  the  boiler. 

The  cylinder  is  somewhat  longer  than  the  stroke 
of  the  piston.  The  space  between  the  piston  head  and 
cylinder  head  when  the  latter  is  at  the  end  of  its 
stroke  is  called  the  clearance;  the  clearance  is  bored 
larger  than  the  diameter  of  the  cylinder  and  is  called 


126  SCIENCE  OF  THRESHING. 

counterbore.  The  counterbore  of  the  cylinder  ends 
is  to  prevent  the  formation  of  shoulders  from  the 
wear  of  the  piston,  and  its  subsequent  pounding, 
which  would  take  place  if  the  cylinder  were  originally 
of  one  diameter  throughout  its  length. 

In  packing  the  stuffing  boxes,  it  is  desirable  that 
the  packing  be  placed  as  evenly  as  possible  around 
the  rods,  and  the  glands  be  drawn  home  as  evenly  as 
possible,  so  as  to  prevent  undue  pressure  on  either 
side  of  the  rods.  Inasmuch  as  the  rod  may  not  run 
exactly  true,  and  is  rarely  of  exactly  the  same  diam- 
eter throughout  its  length,  the  packing  must  be 
elastic.  Long  usage  sometimes  glazes  and  hardens 
the  packing;  when  in  this  condition,  the  gland  should 
not  be  forced  up  as  the  rod  will  become  cut  and  there 
will  be  excessive  friction  and  consequent  loss  of 
power. 

One  side  of  the  crank  disc  is  made  heavier  than  the 
other  to  counterbalance  the  weight  of  the  connecting 
rod  and  reciprocating  parts.  This  is  done  to  prevent 
the  vibration  which  would  otherwise  take  place, 
racking  the  engine  and  alternately  tightening  and 
slacking  the  drive  belt. 

The  journals  on  this  part  of  the  engine  should 
receive  great  care  and  not  be  allowed  to  become 
loose  from  wear  and  thereby  occasion  knocking  and 
pounding.  The  pillow  block  or  bearing  in  which  the 
main  shaft  o»f  the  engine  runs  should  be  kept  suffi- 
ciently tight  so  that  the  shaft  will  run  true  and  also 
to  withstand  the  pressure  of  the  piston  and  connecting 
rod.  The  bearing  may  be  tightened  by  removing  a 


SCIENCE   OF  THRESHING. 


127 


liner  and  screwing  the  cap  down  just  hard  enough  to 
make  the  shaft  run  true  without  causing  a  great  deal 
of  friction. 

There  are  means  of  taking  up  the  wear  in  the 
bearing  brasses  of  the  crank  and  wrist  pin  or  crank 
pin,  as  it  is  more  correctly  called.  These  comprise 
wedges  held  against  the  outer  side  of  the  brasses  by 
encircling  straps,  and  drawn  in  or  out  by  properly 
arranged  screws.  The  brasses  should  not  be  drawn 
so  tightly  as  to  heat  and  cling  to  the  shaft,  the 
particles  of  brass  thereby  becoming  abrading  par- 
ticles. 

It  must  be  remembered  that  taking  up  the  brasses 
in  this  manner  changes  the  length  of  the  connecting 
rod  and  makes  the  clearances  at  the  two  ends  of 
the  cylinder  unequal.  This  must  be  remedied  by  the 
insertion  of  shim  or  liner  plates,  or  by  changing  the 
length  of  the  piston  rod. 

THE  ECCENTRIC. 


Motion  is  imparted  to  the  slide  valve  by  an  eccen- 
tric on  the  main  shaft.  This  consists  of  a  disc,  9,  se- 
cured to  the  shaft  so  that  its  center  does  not  coincide 


128 


SCIENCE   OF   THRESHING. 


with  the  shaft  center.  Tt  therefore  follows  that  this 
center,  O,  describes  a  circle  around  the  shaft,  and  the 
diameter,  W ',  of  this  circle  is  the  throw  of  the  eccen- 
tric. The  eccentric  strap,  10,  which  surrounds  it,  and 
the  eccentric  rod,  u,  will  consequently  travel  back 
and  forth  a  distance  equal  to  this  diameter.  The 
radius  of  this  circle  is  the  radius  of  the  eccentric. 
The  eccentric  is  in  effect  a  crank  and  reciprocates  the 
valve  stem  and  valve.  The  connection  between  the 
eccentric  and  valve  stem  may  be  made  in  a  number  of 
ways. 

THE  SLIDE  VALVE. 


The  D-slide  valve  is  the  most  common  of  the 
valves  used  to  distribute  steam  in  the  engine  cylinder. 
A  section  of  such  valve  is  shown  in  the  figure  in  its 
central  position,  pp  are  the  steam  ports,  oo  the 
bridges,  E  the  exhaust  port,  ST  the  valve  seat.  The 
flanges  of  the  valve,  ab  and  cd,  are  seen  to  be  wider 
than  the  ports  which  they  cover.  Of  this  extra  width 
the  parts  ee  are  called  the  outside  lap,  and  the  parts 
//  the  inside  lap.  F  is  the  valve  stem  connecting 
with  the  eccentric. 

As  the  motion  of  the  valve  is  given  by  the  eccen- 


SCIENCE  OF  THRESHING. 


129 


trie,  the  valve  is  in  mid-position  when  the  radius  of 
the  eccentric  is  vertical.     When  the  radius  is  hori- 


zontal, and  extending  to  the  left,  the  valve  is  in  its 
position  nearest  the  head  end  of  the  steam  chest. 


130  SCIENCE   OF   THRESHING. 

There  are  many  varieties  of  valves;  the  description 
of  the  working  of  one  will  explain  the  operation  of 
all. 

These  figures  show  in  skeleton  the  disposition  of  the 
parts  when  the  piston  is  at  the  different  points  of  the 
stroke.  Of  course,  in  order  to  give  a  clear  view,  the 
comparative  dimensions  of  the  parts  have  been  dis- 
torted. 

The  parts  a,  b,  c,  d,  are  joints  or  journals  to  allow 
the  parts  to  take  proper  positions  in  the  different 
views.  O  is  the  main  engine  shaft  on  which  the 
crank  is  secured. 

A  shows  the  position  of  the  crank,  piston  and  valve 
at  the  beginning  of  the  forward  stroke.  The  valve 
has  just  started  to  open  the  steam  port  at  the  head 
end  to  admit  live  steam  to  the  cylinder,  and  has 
uncovered  the  exhaust  port  to  allow  the  steam  from 
the  inboard  end  of  the  cylinder  to  escape  through  the 
exhaust. 

B  illustrates  the  position  of  the  various  parts  at  the 
end  of  the  first  quarter  of  the  revolution.  The  crank 
is  upright,  both  steam  ports  are  fully  uncovered. 
The  piston  is  more  than  half  way  along  its  stroke,  on 
account  of  the  angularity  of  the  connecting  rod. 

C  shows  the  end  of  the  first  half  of  the  revolution 
with  the  crank  at  the  dead  center,  the  piston  at  the 
end  of  its  stroke,  and  the  valve  covering  the  head  end 
port  against  live  steam,  and  commencing  to  open  the 
exhaust  port  at  that  end,  while  the  port  at  the  inboard 
end  is  just  started  to  open  to  the  live  steam. 


SCIENCE   OF   THRESHING. 


-D  is  the  third  quarter  of  the  revolution,  the  crank 
being  at  the  lowest  point,  and  both  inlet  and  outlet 
ports  being  wide  open. 

E  shows  the  parts  at  the  end  of  the  revolution  in 
the  same  position  as  at  the  starting  point. 

To  compensate  for  the  shortening  of  the  valve 
stem  and  the  eccentric  straps  from  the  take  up  for 
wear,  as  well  as  for  taking  up  the  crank  and  shaft 
bearings,  it  is  necessary  to  set  the  valve  so  that  it  will 
have  even  throw  or  travel  in  relation  to .  the  center 
of  the  engine  stroke. 

THE   GOVERNOR. 

When  an  engine  is  running  at  a  constant  speed  the 
work  done  by  the  steam  in  the  cylinder  must  just 

equal  the  resistance  over- 
come at  the  flywheel  rim. 
Should  the  resistance  be- 
come less  than  the  work,  the 
excess  power  causes  the 
moving  parts  to  move 
faster  and  faster,  and  the 
engine  "races"  or  "runs 
away."  If,  on  the  con- 
trary, the  resistance  at  the 
flywheel  rim  is  greater  than 
the  work  done  in  the  cyl- 
inder, the  engine  slows 
down  and  finally  stops. 
The  work  required  of  an 
engine  does  not,  of  course, 


132  SCIENCE  OF  THRESHING. 

remain  constant,  and  it  is  necessary  to  have  some 
means  for  varying  the  amount  of  steam  to  the 
cylinder  automatically  to  suit  the  work  to  be  done. 
A  device  for  doing  this  is  called  the  "governor." 
One  type  of  governor  is  shown  in  the  figure. 
Two  or  more  controlling  weights  are  so  hung 
as  to  revolve  around  a  stem  and  to  move  outwardly 
therefrom  under  centrifugal  force  against  the  ten- 
sion of  the  springs.  The  spindle  is  rotated  by  a 
pulley  and  a  belt  connection  or  the  like  from  the 
main  shaft  of  the  engine.  The  side  motion  of  the 
balls  moves  the  valve  through  which  the  steam 
must  pass  on  its  way  to  the  steam  chest.  This  is  a 
"balanced  valve"  so  that  its  closure  moves  easily. 
It  is  so  connected  to  the  balls  by  appropriate 
mechanism  that  the  valve  admits  more  steam  when 
the  balls  are  turning  slowly,  as  when  the  engine  is 
running  slowly,  than  when  the  balls  are  rotating 
rapidly  and  so  moving  away  from  the  spindle. 
Thus  steam  is  admitted  in  proportion  to  the  work 
to  be  done,  as  the  increase  in  load  and  slowing 
down  of  the  engine  is  met  by  an  increase  in  the 
steam  admitted  to  the  cylinder,  while  a  decrease  in 
the  load  and  consequent  increase  of  the  engine  speed 
is  counteracted  by  the  shutting  off  of  the  steam. 

SPEED  CHANGER. 

Speed  changers  are  now  provided  for  traction  en- 
gines which  permit  of  the  speed  being  changed  from 
the  foot  board  while  the  engine  is  in  motion. 


SCIENCE   OF   THRESHING. 


TRACTION  ENGINES. 


133 


The  accompanying  figure  shows  the  most  common 
type  of  combined  engine  and  boiler.  The  parts  are 
indicated  by  the  reference  letters.  A,  boiler;  B,  drive 
wheels  or  traction  wheels ;  Cy  front  truck  wheels ;  D, 
bull  gear;  E,  bull  pinion;  F,  main  pinion;  G, 
steering  chain  drum;  H,  steering  drum  bracket;  J, 
steering  chain;  L,  front  axle  or  king  bolt  bracket; 
M,  smoke  stack;  TV,  extension  front  or  smoke  box; 


O,  damper;  Pf  damper  regulator;  Q,  smoke  box 
door;  R,  high  pressure  cylinder;  S,  low  pressure 
cylinder;  T,  steam  supply  pipe;  u,  governor;  a, 
cylinder  lubricator;  b,  governor  belt;  cy  crank  disc; 
df  connecting  rod;  e,  girder  frame;  ft  crosshead;  g, 
piston  rod;  h,  stuffing  box;  it  crank  pin;  Wt  fly- 
wheel; ;,  friction  shoe;  /,  whistle;  m,  safety  valve; 
n,  reverse  lever ;  p}  throttle  valve  lever ;  qt  quadrant ; 
r,  steering  wheel;  ss,  injectors;  tt,  check  valves;  w, 
water  tank;  x,  draw  bar;  yt  draw  bar  spring. 


CHAPTER  XII. 
SETTING  THE  VALVE. 

When  the  engine  is  turned  so  that  the  crank  arm, 
piston  stem  and  cylinder  are  lying  in  line,  as  when  the 
piston  is  at  the  end  of  its  stroke,  the  engine  will  not 
turn  when  the  steam  is  admitted  behind  the  piston, 
as  it  is  pushing  directly  against  the  shaft.  The 
engine  is  then  said  to  be  on  a  dead  center.  Obviously 
there  are  two  dead  centers  corresponding  to  the  two 
extreme  positions  of  the  crank. 

In  order  to  set  the  valve  it  is  often  necessary  to 
place  the  engine  on  its  dead  center.  A  method  of 
doing  this  is  explained  as  follows: 

When  the  crosshead  is  very  near  the  end  of  its 
throw,  make  a  mark  b,  on  one  of  the  guides  opposite 
the  outer  edge  of  the  crosshead.  Now  turn  the  engine 


in  the  direction  of  the  arrow  until  the  outer  edge  of 
the  crosshead  again  comes  in  register  with  the  mark. 


SCIENCE   OF  THRESHING.  135 

/;.  While  the  engine  is  in  this  position,  take  a  tram, 
d,  or  a  common  pair  of  dividers,  and  adjust  its  scratch 
point  at  about  the  height  of  the  center  of  the  crank 
shaft  above  the  floor.  Place  one  end  on  the  floor  or 
engine  bed  and  with  the  scratch  point  make  a  mark,  e, 
upon  the  edge  of  the  flywheel.  The  engine  will  not 
be  on  the  center  exactly;  the  crank  pin  will  be 
slightly  above  the  center.  Turn  the  engine  in  the 
direction  of  the  arrow,  x,  until  the  edge  of  the  cross- 
head  comes  even  with  the  mark,  b,  on  the  guides. 
The  flywheel  will  have  made  nearly  a  revolution  and 
the  crank  pin  be  the  same  distance  below  the  center 
that  it  was  above  it.  The  tram  point  will  now  make 
a  new  mark,  e ,  on  the  rim.  Make  a  mark  on  the  rim 
midway  between  the  mark  e  and  the  mark  e  t  and  then 
turn  the  engine  until  the  center  mark,  f,  is  opposite 
the  tram  point.  The  engine  is  then  exactly  on  its 
dead  center.  Find  the  dead  center  at  the  opposite 
end  in  the  same  way. 

To  set  the  valve,  put  the  engine  on  its  dead  center, 
place  the  valve  on  its  seat  and  connect  it  with  the 
valve  rod;  shift  the  eccentric  on  the  shaft  until  the 
valve  has  the  required  lead.  Turn  the  engine  the 
way  it  is  to  run,  until  it  is  on  the  other  dead  center. 
If  the  lead  is  the  same  as  at  the  other  end  of  the 
throw  or  stroke,  the  valve  is  correctly  set;  if  it  is  not, 
the  valve  rod  must  be  lengthened  or  shortened  until 
the  lead  at  either  end  is  the  same.  If  now  the  lead 
be  too  much,  the  eccentric  may  be  shifted  back  on  the 
shaft;  if  too  little,  it  may  be  shifted  ahead. 

If  the  engine  has  a  reversing  gear,   the  reverse 


136  SCIENCE   OF  THRESHING. 

lever  should  be  set  so  as  to  bring  one  of  the  eccentric 
rods  in  line  with  the  valve  stem,  and  then  proceed  as 
above  directed;  then;  shift  the  lever  and  bring  the 
other  eccentric  stem  in  line,  and  again  set  the  valve; 
in  each  instance  turn  the  engine  for  each  setting  in 
the  way  it  would  normally  run  when  the  parts  are  in 
the  position  given ;  this  turning  the  engine  in  the  way 
in  which  it  should  go  as  you  set  it,  accounts  for  and 
allows  for  any  lost  motion  in  the  parts. 

TRACTION  GEARING. 

Power  is  usually  transmitted  to  the  drive  wheels 
from  the  main  engine  shaft  through  a  train  of  gear- 
ing. This  gearing  is  arranged  to  suit  the  form  and 
equipment  of  the  engine.  It  usually  consists  of  a 
friction  clutch  and  a  main  pinion  which  are  secured 
together  and  run  on  the  main  shaft.  This  main  pinion 
engages  an  intermediate  gear  which  in  turn  engages 
a  compensating  gear.  The  latter  imparts  motion  to 
a  pair  of  bull  gears  which  are  secured  to  the  traction 
wheels,  the  two  gears  being  connected  to  the  compen- 
sating gear  through  an  intermediate  gear.  By  the 
application  of  the  friction  brake  the  engine  is  coupled 
to  the  drive  wheels,  its  motion  being  greatly  reduced 
in  passing  through  the  gearing,  and  thus  the  engine  is 
propelled.  The  compensating  gear  allows  the  two 
traction  wheels  independent  movement  so  as  to  follow 
the  curves  and  irregularities  of  the  road,  whereby 
there  is  no  slipping  of  the  wheels  in  turning  corners, 
and  a  consequent  loss  of  power. 


SCIENCE   OF  THRESHING.  137 

THE  TRACTION  OR  DRIVE  WHEELS. 

The  traction  or  drive  wheels  should  be  of  sufficient 
width  of  tire  or  tread  to  give  good  tractive  power. 
They  are  provided  with  spuds  or  lugs  to  prevent 
slipping  and  are  of  a  variety  of  forms.  The  larger 
the  traction  wheel  in  diameter  the  more  easily  the 
engine  will  traverse  soft  ground. 

A  large  wheel  is  less,  liable  to  slip  and  revolve  on 
the  ground  as  it  has  a  greater  bearing,  owing  to  the 
small  angle  of  contact  presented  to  the  front  side  of 
the  wheel. 


CHAPTER  XIII. 
WHISTLE  SIGNALS. 

The  whistle  can  be  made  to  do  service  if  its 
use  is  rightly  understood,  but  it  is  very  poor  practice 
to  toot  and  blow  it  promiscously  without  any  plan 
or  method.  If  all  threshermen  would  adopt  and 
use  a  prescribed  code  of  signals,  those  connected  with 
the  machine  would  soon  become  accustomed  to  them 
and  understand  what  they  mean. 

The  less  the  whistle  is  used  the  better,  as  it  scares 
high  spirited  horses,  excites  persons  not  accustomed 
to  it,  and  attracts  the  attention  of  all  within  hearing 
from  their  work.  This  time  lost  would  not  be  very 
much  for  one  man,  but  twenty-five  or  one  hundred 
men  losing  from  one-half  to  noe  minute  apiece,  is  an 
item  which  if  multiplied  often  during  the  fall's  run 
will  be  of  enough  magnitude  to  deserve  attention. 

CODE. 

One  long  continuous  sound  is  given  to  attract  atten- 
tion at  such  times  as  in  the  morning  or  at  noon  to 
indicate  the  working  place. 

Two  long  continuous  sounds  with  a  short  interval 
between  them  is  to  denote  the  work  completed  for 
that  day  or  at  that  place,  as  the  case  may  be. 

One  short  sound  is  to  stop. 

138 


SCIENCE   OF  THRESHING.  139 

Two  short  sounds  with  a  short  pause  between  them, 
to  go  ahead  or  commence  work. 

Three  medium  short  sounds  means  to  hurry,  given 
to  indicate  to  those  hauling  grain  that  the  machine  is 
about  to  wait  for  them. 

One  long,  continuous  sound  followed  by  three 
shorter  ones  is  a  signal  to  the  waterman  that  the 
supply  of  water  is  about  exhausted. 

A  continuous  succession  of  short  and  rapid  sounds 
denotes  fire  or  other  distress  and  should  be  responded 
to  by  all  within  hearing  of  the  call. 

No  one  should  ever  sound  the  whistle  but  the 
engineer,  as  one  unaccustomed  to  it  cannot  give  the 
proper  expression  to  the  sound. 

The  stroke  of  the  whistle  lever  should  be  full  and 
steady,  and  well  timed.  The  valve  should  not  be 
opened  too  suddenly,  but  with  a  clean  and  steady  pull, 
and  should  be  closed  gradually.  The  spaces  between 
the  sounds  should  be  well  timed  and  of  equal  length. 
This  will  give  expression  to  the  sound,  pleasing  to 
hear.  An  old  thresherman  once  said  he  could  tell  the 
character  of  the  engineer  by  the  way  he  sounded  the 
whistle. 

The  tone  or  pitch  of  a  whistle  may  be  changed  by 
screwing  the  bell  up  or  down.  The  lower  down  the 
sharper  the  tone  will  be,  and  more  piercing  to  the 
ears  of  those  near  by.  When  the  bell  is  farther  up 
the  tone  will  be  of  lower  pitch  and  can  be  heard  at 
a  greater  distance  and  is  not  so  distressing  to  those 
near  by.  When  set  in  a  position,  it  should  be  left  so 
and  not  changed  without  good  reason,  as  the  people 


140  SCIENCE  OF  THRESHING. 

in  the  neighborhood  become  accustomed  to  it  and  can 
distinguish  whose  machine  is  giving  the  signals. 

Whistles  are  sometimes  made  in  chimes  of  two  or 
more  tones  that  are  very  pleasing  to  the  ear. 


CHAPTER  XIV. 

OPERATING  AND  HANDLING  OF  THE 
ENGINE. 

Reference  has  already  been  made  to  the  care  of 
the  boiler,  and  the  engine  proper,  while  at  work 
requires  as  close  attention  and  careful  handling.  The 
correct  water  level,  uniform  fire  and  constant  steam 
pressure  are  to  be  maintained,  as  before  stated,  and, 
in  addition  to  this,  the  engine,  if  on  the  road,  is  to 
be  guided  and  kept  clear  of  stumps  and  like  obsta- 
cles. Hills  are  to  be  planned  for  and  the  fire  and 
water  arranged  and  regulated  accordingly.  The 
temperature  in  which  a  traction  engine  works  varies 
from  the  heat  of  the  southern  summer  to  the  intense 
cold  of  the  northern  winter,  and  these  facts  must  be 
taken  into  account  in  running  the  machine  and 
keeping  it  in  order. 

STARTING  THE  ENGINE. 

Before  starting  the  engine,  open  the  cylinder  cocks 
and  let  a  little  steam  into  the  cylinder  by  opening  the 
throttle  slightly;  wait  until  the  steam  has  had  time 
to  heat  the  cylinder  and  drive  out  the  water  from  the 
condensed  steam  which  always  forms  when  the  cylin- 
der is  cold.  This  may  form  in  large  quantities,  and  if 
it  gets  in  between  the  cylinder  head  and  the  piston,  its 

141 


142  SCIENCE  OF  THRESHING. 

resistance,  if  the  engine  be  started  suddenly,  throws 
a  severe  strain  on  the  brasses  and  connections,  and 
may  even  fracture  the  cylinder  head. 

After  the  cylinder  has  been  heated  up  at  one  end, 
the  reverse  lever  should  be  thrown  over  to  admit 
steam  to  the  other  end.  If  the  engine  is  a  compound, 
the  reverse  lever  should  be  thrown  back  and  forth  a 
few  times  to  warm  up  the  low  pressure  cylinder. 
After  the  cylinder  has  been  properly  heated,  which  is 
indicated  by  steam  instead  of  water  issuing  from  the 
cylinder  cock,  the  throttle  may  be  opened  enough  to 
cause  the  engine  to  start  slowly.  After  it  has  run 
slowly  for  a  little  time,  the  throttle  should  be  opened 
enough  to  run  it  at  full  speed. 

THE  ENGINE  ON  THE  ROAD. 

While  traveling  on  the  road,  the  water  should  be 
carried  as  high  as  practical  in  the  glass  to  insure  the 
covering  of  the  fire-box  and  the  flues,  while  the  engine 
is  passing  over  any  irregularities  on  the  road.  Before 
starting  to  ascend  long  or  steep  hills,  fresh  fuel 
should  be  added  to  the  fire  in  time  for  it  to  become 
thoroughly  ignited  before  the  steep  portion  of  the 
hill  is  reached.  Fresh  fuel  deadens  the  fire  and 
absorbs  the  heat  of  the  live  coals,  thus  momentarily 
checking  the  generating  of  steam.  If  the  hill  to  be 
ascended  is  a  long  or  steep  one,  and  the  engine  has 
a  heavy  load  to  draw,  the  speed  of  the  engine  should 
be  regulated  to  run  only  fast  enough  to  use  the 
steam  as  generated.  If  the  engine  is  permitted  to 
run  too  fast  when  loaded,  the  steam  pressure  will  be 


SCIENCE   OF  THRESHING.  143 

reduced,  and  as  a  result,  the  engine  will  be  stalled, 
and  there  may  be  trouble  in  getting  it  started  again 
while  on  an  incline.  The  reduction  of  the  steam 
pressure  so  suddenly  while  a  hot  fire  is  burning  is 
very  liable  to  cause  foaming  or  priming,  and  is  also 
hard  on  the  joints  and  weak  portions  of  the  boiler. 
The  proper  plan  is  to  watch  the  steam  gauge  closely 
and  keep  the  speed  only  fast  enough  to  maintain  the 
steam  pressure  sufficiently  high  to  insure  the  working 
of  the  engine.  When  the  engine  is  working  at  its 
fullest  capacity,  the  reverse  lever  may  be  thrown 
over  to  the  last  notch  on  the  quadrant  to  permit  the 
cylinder  to  be  filled  with  live  steam  during  the  great- 
est portion  of  the  stroke  possible,  and  thus  prevent 
the  engine  from  becoming  stalled. 

In  passing  down  hill,  the  reverse  lever  may  be 
hooked  up  near  the  center.  If  the  hill  is  so  steep 
that  the  engine  has  a  tendency  to  increase  its 
speed,  the  throttle  should  be  closed  and  the  engine 
should  be  reversed;  the  piston  will  then  cushion 
itself  on  the  air  in  the  cylinder  and  so  retard  the  speed. 
In  case  this  is  not  a  sufficient  check,  the  throttle  may 
be  opened  slightly  to  admit  a  little  steam  and  the 
reverse  lever  moved  to  a  point  where  the  desired 
speed  of  the  engine  will  be  maintained. 

While  on  the  road  it  is  poor  practice  to  take  off  the 
governor  belt  and  try  to  control  the  speed  of  the 
engine  by  the  throttle  or  to  run  it  at  a  greatly 
increased  rate,  as  the  vibration  and  jar  of  the  oscil- 
lating parts  cause  strain  and  undue  wear  on  the 
connecting  parts.  If  it  is  desired  to  change  the  speed, 


144  SCIENCE   OF  THRESHING. 

it  should  be  done  by  the  governor;  this  will  allow  the 
engine  to  run  at  the  desired  speed  without  fear  of 
being  run  too  fast. 

GUIDING  THE    ENGINE. 

When  traveling  on  the  road,  the  engine  is  made  to 
turn  by  swinging  the  front  axle  as  in  a  wagon,  by 
means  of  the  guide  wheel  and  steering  chain  gear. 
By  cramping  the  wheels  more  or  less,  a  longer  or 
shorter  turn  is  made. 

To  find  the  space  required  to  turn  the  engine 
around  completely,  when  the  front  wheels  are 
cramped  at  a  given  angle  or  position,  set  the  wheels 
at  the  required  angle  and  then  draw  a  line  on  the 
ground  beneath  and  in  a  line  with  the  front  axle,  also 
draw  a  line  under  and  in  line  with  the  rear  axle.  The 
intersection  of  these  lines  will  be  the  center  of  the 
circle  in  which  the  engine  will  travel  when  the  wheels 
are  set  in  a  given  position  and  double  the  distance 
from  this  center  to  the  engine  will  be  the  diameter  or 
width  of  the  circle. 

THE   FRICTION  CLUTCH. 

To  set  the  train  of  traction  gearing  in  motion,  and 
thus  start  the  engine  traveling,  the  flywheel  is  first 
put  in  motion  and  then  the  friction  clutch  is  thrown 
into  engagement  with  it.  The  motion  of  the  engine 
shaft  is  thus  transmitted  through  the  clutch  and  gears 
to  the  driving  wheels.  In  using  the  friction  clutch, 
care  should  be  taken  not  to  throw  it  in  gear  too 
suddenly,  as  the  strain  on  the  gearing  and  connections 


SCIENCE   OF   THRESHING.  145 

is  very  severe.  The  ordinary  traction  engine  weighs 
from  four  to  twelve  tons  and  to  set  this  great  weight 
in  motion  suddenly  puts  an  enormous  load  on  the 
driving  mechanism. 

The  engine  should  be  started  slowly.  The  fric- 
tion clutch  may  be  then  thrown  in  gradually  until  the 
traction  gearing  is  set  in  motion  when  the  clutch  may 
be  sent  home  and  the  throttle  opened  sufficiently 
to  give  full  speed  to  the  engine. 

The  friction  shoes  of  the  clutch  should  be  just  tight 
enough  to  insure  proper  driving  of  the  engine  without 
slipping;  if  too  tight,  there  is  undue  strain  and  wear 
on  the  parts  which  come  in  contact  with  the  wheel. 

SETTING   THE    ENGINE. 

When  setting  the  engine  in  line  with  the  separator, 
the  flywheel  of  the  engine  and  drive  pulley  of  the 
separator  should  be  placed  in  line  and  near  enough  to 
each  other  so  that  the  drive  belt,  when  placed  thereon, 
is  not  too  loose.  The  engine  is  then  started  and  the 
friction  clutch  is  thrown  in  for  a  moment,  causing  the 
engine  to  travel  backwards  and  tighten  the  belt 
sufficiently  to  drive  the  separator.  The  engine  is  then 
blocked  to  prevent  it  from  moving  ahead  when  the 
clutch  is  released,  as  it  would  otherwise  do,  owing 
to  the  tension  of  the  drive  belt. 

GEAR  LOCK. 

If  a  gear  lock  is  on  the  engine,  it  should  be  thrown 
in  before  the  engine  is  started  backwards. 

The  engine  should  be  set  nearly  even  or  level  for 
threshing  or  other  stationary  work.  The  rear  end 


146  SCIENCE  OF  THRESHING. 

should  be  somewhat  lower  than  the  forward;  the 
engine  should  never  be  inclined  the  other  way,  as  the 
steam  dome  is  near  the  forward  end  of  the  boiler. 
The  elevation  of  the  front  end  will  give  a  greater 
distance  from  the  steam  pipe  to  the  water  line;  this 
positioning  of  the  engine  is  perhaps  more  essential 
in  boilers  having  little  steam  space  than  those  having 
large  space. 


CHAPTER  XV. 
TESTS  FOR  LEAKS. 

The  cylinder  rings  and  the  valve  should  be  occa- 
sionally tested  to  see  that  they  are  steam  tight. 
Should  the  piston  or  valve  leak  very  much  steam  the 
economy  or  efficiency  of  the  engine  will  be  considera- 
bly lessened.  The  steam  that  leaks  through,  besides 
being  wasted,  interferes  with  the  free  working  of  the 
engine  by  choking  the  ports  and  exhaust,  thus  causing 
high  back  pressure.  If  an  engine  is  allowed  to  do 
much  leaking  the  results  are  far  reaching.  The  ports 
and  exhaust  being  unduly  filled,  the  engine  has  to  do 
more  work  to  overcome  the  back  pressure  on  the 
piston  and  this,  of  course,  means  that  the  governor  is 
admitting  an  extra  supply  of  steam  to  keep  up  the 
speed.  ,We  thus  have  a  double  loss — the  steam 
leaking  through,  and  the  steam  used  in  excess  of  the 
normal  to  overcome  the  resistance.  This  excess  of 
steam  calls  for  an  extra  amount  of  feed  water  to  be 
forced  into  the  boiler,  an  extra  amount  of  fuel  to  be 
burned,  and  an  extra  high  temperature  to  which  the 
fire-box  and  plate  are  subjected.  The  engine  and 
boiler  are  thus  required  to  dp  an  extra  amount  of 
work,  which  in  some  old,  worn  engines  may  be  nearly 
fifty  per  cent  of  the  actual  work  performed. 

The   piston   and   valve   may  be   easily   tested   as 

H7 


148  SCIENCE  OF  THRESHING. 

follows:  Place  the  engine  slightly  off  the  center  in 
the  direction  it  is  intended  to  run,  a  sufficient  distance 
to  insure  the  steam  port  being  open  to  admit  the  live 
steam  to  the  cylinder;  take  a  strong  chain  and  fasten 
to  the  rim  of  the  flywheel  adjacent  to  one  of  its 
spokes,  and  secure  it  to  some  stationary  part  of  the 
engine  in  such  a  manner  that  when  the  throttle  is 
opened,  and  steam  is  admitted  to  the  cylinder,  the 
flywheel  cannot  revolve,  but  resists  the  pressure  of 
the  steam  on  the  piston.  With  the  engine  in  this  posi- 
tion and  the  throttle  open,  we  have  full  boiler  pres- 
sure on  one  side  of  the  piston  and  the  other  side 
exposed  to  the  atmosphere  through  the  exhaust  ports 
and  pipes.  By  placing  the  hand  over  the  exhaust 
nozzle,  at  the  base  of  the  smokestack,  any  leakage  of 
the  steam  through  the  cylinder  rings  or  valve  seat 
may  be  easily  detected.  If  much  steam  is  escaping, 
the  valve  seats  and  rings  should  have  attention; 
however,  the  most  perfectly  fitted  engines  will  leak 
some. 

If  the  engine  is  found  leaking,  the  next  step  is  to 
determine  whether  it  is  through  the  valve  seat  or 
cylinder  rings.  This  may  be  done  as  follows.  Place 
the  engine  slightly  off  the  exterior  dead  center  in  the 
direction  intended  to  run,  which  will  open  the  steam 
port  at  the  crank  end  of  the  cylinder.  Chain  the 
flywheel  as  before  and  remove  the  cylinder  cap. 
With  the  engine  in  this  position  and  the  throttle  valve 
open,  and  steam  pressure  on  the  valve  and  on  the 
piston  in  the  crank  end  of  the  cylinder,  the  point  of 
leakage  can  be  easily  detected.  If  the  steam  escapes 


SCIENCE   OF  THRESHING.  149 

from  the  head  end  steam  port  leading  to  the  valve 
seat,  it  clearly  indicates  that  the  valve  is  leaking;  if 
the  steam  escapes  around  the  piston  head,  it  is  plain 
that  the  cylinder  rings  are  leaking. 

It  is  a  good  plan  to  test  the  piston  and  valve  in 
different  positions,  as  in  some  positions  they  are  found 
to  leak  while  in  others  they  are  perfectly  tight.  This 
is  owing  to  the  fact  that  the  cylinder  does  not  wear 
evenly. 

In  testing,  great  care  should  always  be  taken  to 
have  the  flywheel  firmly  secured,  as  play  of  a  few 
inches  might  break  the  chain  and  do  injury  to  the 
operator. 

If  the  valve  is  found  to  be  leaking,  it  may  be 
repaired  by  planing  the  valve  and  valve  seat,  and 
afterwards  scraping  to  a  true  surface  by  means  of  a 
scraper  and  surface  plate. 

If  the  cylinder  rings  are  found  to  be  leaking,  they 
should  be  expanded  or  replaced  by  new  ones ;  cylinder 
rings  in  pistons  which  are  constructed  with  an  inside 
ring  and  stud  bolts  for  the  purpose  of  forcing  the 
rings  outwardly  to  the  wall  of  the  cylinder,  are  the 
only  ones  that  can  be  expanded  successfully.  In  other 
forms  of  pistons  and  rings  where  a  groove  is  turned 
in  the  piston,  and  the  rings  are  sprung  into  place  and 
held  by  their  own  elasticity,  the  usual  practice  is  to 
replace  the  rings  by  new  ones. 

In  compound  engines  the  same  general  plan  of 
testing  the  engine  may  be  followed,  but  it  is  some- 
times more  difficult  to  locate  the  exact  point  of  the 
leakage,  on  account  of  the  multiplicity  of  the  ports 
and  working  parts. 


CHAPTER  XVI. 

FRICTION  AND  LUBRICATON. 

The  rubbing  of  the  surface  of  one  body  against 
that  of  another  produces  friction.  Friction  varies 
greatly  with  different  materials,  conditions  of  the 
surfaces  in  contact  and  the  weight  bearing  them 
together.  The  friction  between  two  pieces  of  pol- 
ished steel  is  much  less  than  between  two  pieces  of 
brick. 

The  power  expended  in  overcoming  friction  is 
transformed  into  heat,  and  the  greater  the  friction 
between  two  surfaces  the  greater  the  quantity  of  heat 
produced. 

Friction  is  caused  between  two  surfaces  by  the 
unevenness  and  roughness  of  the  surfaces  in  contact. 
No  matter  how  smooth  a  journal  or  box  may  seem  to 
be,  the  surface  is  dotted  all  over  with  minute  points 
or  projections,  with  indentations  or  depressions 
between  them. 

When  the  two  metals  of  the  journal  come  in 
contact,  the  points  of  one  of  the  bodies  settle  down 
and  fit  into  the  depressions  of  the  other,  and  when  the 
bodies  are  moved  in  relation  to  each  other  the  points 
cling  fast,  and  some  of  them  break  off,  thus  wearing 
the  surface  away. 

By  the  application  of  properly  shaped  particles 

150 


SCIENCE   OF   THRESHING.  151 

between  the  points  or  projections  of  two  contacting 
metals,  the  pieces  may  be  moved  with  much  less  re- 
sistance or  friction.  Lubricating  oils  or  greases  are 
used  to  supply  these  particles.  The  globules  of  the 
lubricating  material  tend  to  hold  the  surfaces  of 
the  metals  apart,  permitting  the  small  projections  to 
pass  each  other  without  touching,  thus  reducing  the 
friction  and  wear.  The  materials  best  adapted  for 
lubricating  purposes  are  those  whose  globules  retain 
their  natural  shape  under  the  greatest  pressure.  This 
property  of  lubricating  oils  and  greases  is  called 
viscosity.  The  lubricant  in  a  revolving  journal  will 
lose  its  viscosity  after  a  time,  and  permit  the  surfaces 
to  come  in  contact;  for  this  reason  it  is  necessary  that 
a  fresh  supply  of  oil  be  fed  to  the  journal  to  replenish 
the  old  oil. 

The  cylinder  rings  and  valve  seats  require  special 
lubricating  oil,  capable  of  resisting  the  heat  to  which 
the  parts  are  exposed.  Cylinder  oil  should  resist  a 
temperature  much  higher  than  the  steam  temperature 
before  its  particles  become  dissociated  or  evaporate. 
If  cylinder  oil  is  so  light  or  volatile  that  as  soon  as 
it  is  exposed  to  the  high  temperature  of  the  steam  the 
liquid  portion  evaporates,  leaving  a  dry,  sooty  like 
residue,  it  is  valueless  as  a  lubricant  and  a  positive 
injury  to  the  face  of  a  valve  or  cylinder  ring. 

Cylinder  oil  may  be  easily  tested  by  putting  a  small 
quantity  on  a  steam  pipe  under  boiler  pressure,  whose 
heat  is  therefore  equal  to  the  engine  cylinder.  If 
the  oil  boils,  smokes  or  evaporates  quickly,  it  is  unfit 
for  cylinder  lubrication.  Put  a  little  oil  such  as 


152  SCIENCE   OF  THRESHING. 

kerosene  or  light  machine  oil  on  such  a  pipe,  and  see 
how  rapidly  it  evaporates  and  disappears  in  smoke 
and  gas. 

The  cylinder  "lubricators"  should  furnish  a  con- 
tinuous supply  of  oil  to  the  engine.  This  supply 
should  be  constant  although  a  small  quantity  will 
suffice  to  keep  the  valve  and  cylinder  rings  lubricated. 
From  three  to  five  drops  per  minute  of  best  grades  of 
cylinder  oil  will  keep  the  ordinary  traction  engine  well 
lubricated,  while  with  lighter  grades,  from  five  to 
seven  drops  should  be  used. 

Gearing  which  has  to  withstand  a  heavy  pressure 
on  the  face  of  its  teeth  should  be  lubricated  with  some 
kind  of  hard  oil  or  axle  grease. 

In  recent  years  hard  oil  has  come  into  general  use 
for  journal  lubrication. 


CHAPTER  XVII. 

WINTER  CARE  OF  THE  ENGINE. 

If  an  engine  is  not  in  use  it  should  be  stored  in  a  dry 
shed  to  prevent  deterioration  caused  by  rust  and 
dampness.  It  should  be  cleaned  of  all  dirt.  The 
smoke  stack  and  outside  of  the  boiler  should  have  a 
coat  of  linseed  oil  to  prevent  rusting.  The  inside  of 
the  boiler  should  be  cleaned,  the  handhole  plates 
should  be  fastened  in  again  and  all  valves  and  con- 
nections kept  closed,  to  exclude  air.  The  boiler  will 
not  rust  or  corrode  on  the  inside,  if  kept  air  tight. 

The  piston  rod  and  valve  stem  should  be  coated 
with  some  non-corroding  oil  and  the  engine  should  be 
left  in  position  with  the  piston  at  the  end  of  the  back 
stroke;  this  leaves  the  piston  rod  housed  in  the 
cylinder.  The  cocks  should  be  kept  closed  to  exclude 
air  and  prevent  rust. 

All  pipes  and  valves  should  be  well  drained  to 
guard  against  bursting  or  straining  by  freezing. 

If  the  boiler  has  formed  much  scale  on  its  heating 
surface,  the  most  of  it  will  loosen  and  drop  off  during 
the  idle  season  by  the  unequal  expansion  of  the  iron 
and  the  scale  from  changes  of  temperature.  The 
loosened  scale  should  be  removed  from  the  boiler 
before  starting  the  engine  again. 


153 


CHAPTER  XVIII. 

SOME  SEPARATOR  AND 
ENGINE  "DONT'S." 

Don't  use  too  many  concave  teeth  in  dry  straw. 

Don't  run  with  loose  cylinder  teeth. 

Don't  try  to  thresh  tough  grain  with  too  few 
concave  teeth,  or  with  the  concave  set  too  low. 

Don't  run  belts  too  loose  or  too  tight. 

Don't   forget  to  keep  all  nuts  tight. 

Don't  run  journals  too  loose  or  too  tight. 

Don't  have  too  much  blast  at  the  back  end  of  the 
sieve. 

Don't  have  too  little  blast  at  the  front  end  of  the 
sieve. 

Don't  try  to  do  good  work  with  the  separator  set 
out  of  level. 

Don't  allow  the  separator  to  rock  back  and  forth 
while  threshing. 

Don't  allow  pitchers  to  overcrowd  the  separator. 

Don't  allow  the  separator  to  run  with  too  little 
grain. 

Don't  use  too  many  sieves. 

Don't  return  many  tailings  to  the  cylinder. 

Don't  have  too  much  end  play  in  the  cylinder 
boxes. 

SOME   ENGINE   "DON'TS." 

Don't  carry  too  deep  a  fire. 
154 


SCIENCE   OF   THRESHING.  155 

Don't  allow  the  ashes  to  accumulate  under  the 
grates. 

Don't  allow  the  spaces  between  the  grates  to 
become  choked  with  cinders. 

Don't  stir  the  fire  enough  to  cause  small  particles 
of  unburnt  coal  to  fall  through  the  grates. 

Don't  allow  vacant  spaces  on  the  grates. 

Don't  have  the  fuel  spread  unevenly  on  the  grates. 

Don't  allow  mud  and  scale  to  accumulate  on  the 
heating  surface  of  the  boiler. 

Don't  neglect  to  keep  the  flues  clean  from  soot. 

Don't  pump  cold  water  into  the  boiler  too  rapidly. 

Don't  run  with  too  low  water. 

Don't  carry  water  high  enough  to  cause  priming 
or  foaming. 

Don't  forget  to  put  out  your  fire  if  water  gets 
below  crown  sheet. 

Don't   forget  to  drain  pipes  in  freezing  weather. 

Don't  forget  to  open  the  boiler  stopcock  before 
starting  the  pump. 

Don't  fail  to  keep  your  water  glass  tubes  and 
cocks  clear  and  open. 

Don't  try  to  work  the  pump  when  the  tank  is 
empty. 

Don't  run  the  engine  with  stuffing  box  glands  too 
tight. 

Don't  fail  to  replace  old  burnt  and  hard  packing 
with  new. 

Don't  fail  to  test  your  piston  and  valve  for  leaks. 

Don't  run  an  engine  with  valve  set  improperly. 

Don't  fail  to  adjust  brasses  and  journals. 


156  SCIENCE   OF  THRESHING. 

Don't  tinker  with  valves  that  are  set  properly. 

Don't  fail  to  keep  all  wearing  parts  well  lubri- 
cated. 

Don't  fail  to  keep  all  other  parts  clean  and  free 
from  oil. 

Don't  run  an  engine  and  separator  out  of  line. 

Don't  run  main  drive  belt  too  loose. 

Don't  neglect  the  rig  when  not  in  use. 

Don't  forget  to  make  the  most  of  your  opportu- 
nities. 


CHAPTER  XIX. 

A  SUGGESTION. 

A  Suggestion  as  to  soliciting  threshing.  Go  about 
it  in  a  business-like  way.  When  you  meet  the  man 
that  has  a  job  that  you  want,  ask  him  for  it  in  a  plain, 
practical  manner.  Assure  him  that  you  will  do  him 
a  good  job  in  a  workmanlike  way  and  save  his 
grain,  and  do  it  in  as  short  a  time  as  is  consistent  with 
good  work.  The  subject  of  price  usually  comes  up 
at  this  time  and  this  is  the  best  time  to  lay  the  founda- 
tion for  prompt  collections. 

Let  your  rule  be  one  price  to  everybody  and  the 
account  cash  as  soon  as  work  is  done,  unless  there  is 
reason  for  an  extension.  Be  sure  to  have  this  under- 
stood at  the  time,  just  when  and  how  the  account  is 
to  be  paid.  This  is  business  and  no  one  ought  to  take 
offense  at  it;  but  if  nothing  is  said  and  the  work  is 
done,  the  parties  to  the  transaction  may  have  entirely 
different  ideas  as  to  the  price  and  time  of  payment. 
This  often  leads  to  difficulties  that  require  some 
sacrifice  to  adjust,  and  the  farmer  feeling  miffed,  will 
resolve  to  do  business  with  some  one  else  next  time, 
all  because  the  start  was  not  made  right. 

There  is  no  more  reason  why  a  thresherman  should 
wait  for  his  money  than  anyone  else.  He  has  his  cap- 
ital invested  and  has  to  pay  his  help  as  he  goes  along. 

157 


158  SCIENCE   OF   THRESHING. 

It  is  usually  the  thresherman's  own  fault  if  he  has 
poor  collections,  for  not  being  firm  and  exact.  He 
would  better  lose  a  job  now  and  then  than  to  lose  the 
pay  after  he  has  done  the  work. 


SCIENCE  OF  THRESHING. 


159 


TABLE  OF  THE  AREAS  AND  CIRCUMFERENCES  OF 
CIRCLES  AND  OF  THE  SIDES  OF  SQUARES  OF  THE 
SAME  AREA. 


01 

c 

a/ 

<J 

o 

w 

c 

** 

CD    W 

41 

.  £  ™ 

*g  oj  £ 

"o  c3  K" 

•  "o  _£ 

f| 

0.2- 

"o  "  o1 

III 

|c 

gig1 

2  o 

3<W« 

0)    !_, 

£  S 

$j       ' 

aj  w 

«-"  C 

2   « 

^     .£ 

33   .  §j 

0  .5 

V  "o 

<U  c 

55  .  §> 

rj 

02  <| 

u 

VL< 

1 

3.14 

.785 

.89 

21 

65.97 

346.36 

18.61 

y2 

4.71 

1.767 

1.33 

y2 

67.54 

363.05 

19.05 

2 

6.28 

3.142 

1.77 

22 

69.11 

380.13 

19.50 

Ys 

7.85 

4.909 

2.22 

y2 

70.68 

397.61 

19.94 

3 

9.42 

7.069 

2.66 

23 

72.25 

415.48 

20.38 

y, 

10.99 

9.621 

3.10 

y2 

73.82 

433.74 

20.83 

4 

12.56 

12.566 

3.54 

24 

75.39 

452.39 

21.27 

% 

14.13 

15.904 

3.99 

~Vz 

76.96 

471.44 

21.71 

5 

15.90 

19.635 

4.43 

25 

78.54 

490.88 

22.16 

y2 

17.27 

23.758 

4.87 

y2 

80.10 

510.71 

2'2.60 

6 

18.84 

28.274 

5.32 

26 

81.68 

530.93 

2.3.04 

y. 

20.42 

33.183 

5.76 

y2 

83.25 

551.55 

23.49 

7 

21.99 

.38.485 

6.20 

27 

84.82 

572.56 

23.93 

% 

2.3.56 

44.179 

6.65 

y2 

86.39 

593.96 

24.37 

8  " 

25.13 

50.266 

7.09 

28 

87.96 

615.75 

24.81 

y2 

26.70 

56.745 

7.53 

y2 

89.53 

637.94 

25.26 

9 

28.27 

63.617 

7.98 

29 

91.10 

660.52 

25.70 

y» 

29.84 

70.882 

8.42 

y2 

92.67 

683.49 

26.14 

10 

31.41 

78.540 

8.86 

30 

94.24 

706.86 

26.59 

y., 

32.98 

86.590 

9.30 

y2 

95.81 

730.62 

27.03 

11 

34.55 

95.03 

9.75 

31 

97.38 

754.77 

27.47 

% 

36.12 

10.3.87 

10.19 

y2 

98.96 

779.31 

27.92 

12 

37.69 

113.10 

10.63 

32 

100.5 

804.25 

28.36 

y2 

39.27 

122.72 

11.08 

y2 

102.1 

829.58 

28.80 

13 

40.84 

132.7.3 

11.5? 

33 

103.6 

855.30 

29.25 

y» 

42.41 

143.14 

11.96 

y2 

105.2 

881.41 

29.69 

14 

43.98 

153  94 

12.41 

34 

106.8 

907.92 

30.13 

y2 

45.55 

165.13 

12.8i 

y2 

108.3 

934.82 

30.57 

15 

47.12 

176.72 

13.29 

35 

109.9 

962.11 

.31.02 

y2 

48.69 

188.69 

13.74 

y2 

111.5 

989.80 

31.46 

16 

50.26 

201.06 

14.18 

36 

113.0 

1017.88 

31.90 

y2 

51.83 

213.83 

14.62 

y2 

114.6 

1046.35 

32.35 

17 

53.40 

226.98 

15.07 

37 

116.2 

1075.21 

32.79 

3/2 

54.97 

240.53 

15.51 

y2 

117.8 

1104.47 

33.23 

18 

56.54 

254.47 

15.95 

38 

119.3 

1134.12 

33.68 

y2 

58.11 

268.80 

16.40 

y2 

120.9 

1164.16 

34.12 

19 

59.69 

283.53 

16.84 

39 

122.5 

1194.59 

34.56 

61.26 

298.65 

17.28 

y2 

124.0 

1225.42 

35.01 

20 

62.83 

.314.16 

17.72 

40 

125.6 

1256.64 

35.45 

y2 

64.40 

330.06 

18.17 

y2 

127.2 

1288.25 

35.  S9 

INDEX. 


PAGE. 

AIR— 

Amount  of  required  for  combustion 92 

Elasticity  of 106 

ASHES     119 

ATMOSPHERE,  Pressure  of 106 

BABBITT— 

Composition  of 68 

Filling  boxes  with 68 

Pouring    69 

Shimming  boxes  for 68 

Temperature  of 69 

BAND  CUTTERS  76 

BARLEY— 

Adjustment  for 50 

BEATER— 

Construction   of    23 

Office  of 23 

Position  of 23,  24,  50 

Speed  of '. 24 

BELTS—  » 

Double    66 

Kinds  of 64,  65 

Lacing 65,  66 

161 


I  62  SCIENCE   OF  THRESHING. 

PAGE. 

Operation  of 9,  67,  72 

Punch  for 6^ 

Size  of  punch  for 66 

Spacing  holes  for  lacing  of 66 

Tension  of 52,  64 

Using    64 

BLOWER— 

Use  of   1 1 6 

BL  AST- 
Adjustment  of   • .  .  . 60 

Angle  of '.  .  .33,  34,  38,  61 

Conditions  of 3  <; 

Difference  between  strength  and  speed  of 57 

Direction  of 33,  59 

Law  of 36 

Office  of 35 

Rule  of 56,   57 

Speed  of 36 

Strength  of 32,  35,  36,  39 

Testing  of 59,  60 

BOILER— 

Blowing  off .  1 1 6 

Care  of 114 

Classes  of 103,  104 

Cleaning 93,   105,    116 

Construction   of    105 

Definition  of 103 

Description  of 103 

Jacketing    1 1 6 

Used  for  engine  frame 120 


SCIENCE    OF    THRESHING.  163 

PAGE. 

BOXES  OF  THE  SHOE 54 

BRASSES— 

Adjustment  of   127 

BRITISH  THERMAL  UNIT— 

Definition  of 88 

B.  T.  U.- 

Definition  of 88 

CHAFFER— 

Operation  of 56 

What  it  is 33 

Wooden    61 

CHECK  BOARD— 

Adjustment  of 24,  5 1 

Position  of 24 

CLEANING  MILL 32 

CLEARANCE,  PISTON 125 

CLUTCH,  FRICTION 144 

COAL— 

Amount  of  heat  in 88 

Combustion  of 91 

Composition  of 91 

Theory  of  combustion 91 

CONCAVE— 

Adjustment  of 19,  20,  21,  49,  51,  55 

Construction  of 19 

Position  of 21 

Teeth  of n,    12 

CRANK— 

Description  of 123,  129 

Disc  .126 


164  SCIENCE    OF    THRESHING. 

PAGE. 

Motion  of 122 

CREW— 

Manager  of 74 

CYLINDER,  ENGINE  121 

CYLINDER,  SEPARATOR— 

Action  of   ii 

Adjustment  of 15,  48,  55 

As  a  balance  wheel 1 5 

Backlashing  of 23 

Balance  of    16 

Boxes  of 48 

Construction   of    . 14 

Draft  of 22 

How  to  balance 16,  17 

Power  consumed  by 44 

Power  of 1 6 

Side  play  of 18 

Slugging 21 

Speed  of 15,  43,  49,  50 

Striking  force  of 44 

Teeth 1 5  <  4$ 

DEAD  CENTER- 
HOW  to  find 135 

DONT'S— 

Engine.  . 154,    155,    156 

Separator    154 

ECCENTRIC— 

Description  of 127,   128 

Motion  of    127 


SCIENCE    OF    THRESHING.  165 

PAGE. 

ENERGY— 

By  heat 84,  86 

ENGINE— 

Adjustment  of    , 71 

Cylinder    121 

Cylinder  rings 149,   151 

Explanation  of 121 

Guiding    144 

Leaking  of 147,   148,   149 

On  the  road 142 

Parts  of 123,    124,    133 

Rocking  to  and  fro 52 

Setting    145 

Starting    141 

The  steam    121 

Traction 133 

FAN — 

Construction   of    34 

Operation  of 58,  59 

Overblast    35 

Sound  of 58 

Underblast 35,  60 

Wear  of 59 

FEED  BOARD — 

Position  of 22 

Shape   of    22 

FEEDERS— 

The  working  of 75 

FEEDING — 

Plan  of    1 8,  43 


1 66  SCIENCE    OF    THRESHING. 

PAGE. 

Speed  of 26 

Uniform 43,  44 

FIRE  Box- 
Construction  of    89 

FIRING- 
HOW  done ii  6,   118 

FIREWOOD— 

Composition  of 93 

FLAIL 1 1 

FLAX- 

Adjustment  for 49,   63 

Cleaning 62 

FOAMING    117 

FOOT  POUNDS— 

Definition  of 88 

Equivalent  to    88 

FRICTION    150 

FRICTION  CLUTCH 144 

FUEL— 

Burning  of 89 

Comparative  weight  and  value 94 

Energy  of 89 

Extra   amount  required 116 

Firewood    93 

Straw    94 

GAUGE— 

Glass    114 

Position  of 114 

Steam 113 

Watching    115 


SCIENCE    OF    THRESHING.  167 

PAGE. 

GEARING— 

Compensating 136 

Strains  on 144 

Traction    136 

GEAR  LOCK 145 

GETTING  READY 71,  72 

GOVERNOR— 

Requirements  of 131 

Speed  changers  of 132 

GRAIN— 

Cracking 48,  49,  62 

Different  kinds 55 

Out  of  straw 52 

Threshed  clean 48 

Varied  conditions  of 47 

Wasting 15,  20,  53,  78 

GRATES,   FURNACE 1 1 1 

GRATES,  SEPARATOR— 

Position   of 21,    50 

GRAVITATION— 

In  separation    28 

Law  of 25 

HEAT- 

Amount  of  in  coal 88 

Applied  to  water 85 

Conduction  of    93 

Evolved  by  fuels ,...92 

Latent 87,89,  90 

Quantity  of 88 

Specific    87 


1 68  SCIENCE    OF    THRESHING. 

PAGE. 

Theory  of 83 

Work  produced  by 83,  84,  89 

ICE— 

Heat  to  melt 89,  90 

INJECTOR— 

Description  of    no 

Leaks  of no 

JOURNALS— 

Care  of 126,  127 

LACE  LEATHER 67 

LEAKS,  ENGINE— 

Testing    for 147 

LEVER,  REVERSE  143 

LUBRICATION— 

Cylinder,  engine 71 

Hard  Oil 71 

Kinds  of 70 

Theory  of 150,  151 

MACHINE  FRAME,  BOLTS  AND  NUTS 72,  73 

OATS,  SEPARATION 49,  50 

OILS — 

Kinds  of 152 

Tests  for 151 

OPERATION— 

Boiler  of 115 

Separator 47,  48 

PACKING    126 

PISTON  122 

PITCHERS 76 

PLUGS.  FUSIBLE  .  .in 


SCIENCE    OF    THRESHING.  169 

PAGE 

POWER    49 

PULLEYS,  CROWNED   67 

PUMPS— 

Kinds  of  .  .  . 107 

Leaks    .  . 109 

Operation  of 107,   108,  109 

Parts  of    107 

PRIMING 117 

RACK— 

Combination 31 

Forms  of    27 

Length  of  stroke 29 

Motion    of 28,    29 

RADDLES— 

Combination  of    31 

Construction   of 30 

Motion  of    30 

REVERSE  LEVER 143 

RUST    51 

RYE,  SEPARATING  51 

STACKERS 42 

SAFETY  VALVE— 

Area  of .'...112 

Description  of 112 

Rules  for  are 112 

SCALE,  EFFECTS  OF 116,  119 

SELF  FEEDER — 

Explanation  of 44 

Governor  for 45 

Office  of 45 


1 70  SCIENCE    OF    THRESHING. 

PAGE 

Operation  of 45,  46 

Power  required  for 46 

Work  of 45 

SEPARATION— 

Aids  to 31 

Best  methods  of    30 

By  Gravity 25 

How  done 28,   30,  31 

Limit  of 26 

Movement  of  stalks  in 25 

Of  oats 50 

Process  of 25,  26,  50 

SEPARATOR— 

Adjustment  for  dusty  grain 51 

Adjustment  for  rye 51 

Capacity  of 26 

Care  of 71 

Lubrication  of    70 

Parts  of 14 

Stands  still 17,   51,  52 

Work  of 13 

SHOE  OR  CLEANING  MILL— 

Motion  of 53 

Operation  of 56,  57  ,61 

Speed  of 53 

SIEVES— 

Adjustable 33 

Adjustment  of 61,  62 

Construction  of 32,  33,  34,  35 

Flax    63 


SCIENCE    OF    THRESHING.  171 

PAGE 

Kinds  of 32,  61 

Meshes  of 33 

Motion  of 32,  34,  37,  38,  39 

Number  of 32,   62 

Openings  in 34 

Overloading    37 

Variety  of 61 

Ov/v-J  -L  ' 

Effects  of 1 1 6 

SPEED  CHANGER 132 

SPEED  FOR  RUSTY  OATS 51 

STEAM— 

Getting  up 115 

Heat  of 85 

How  used 122,    124 

Produced  by  Heat 85 

Properties  of 96 

Saturated    96 

Tables 98,  99,  100 

STRAW— 

Action  on 20 

Broken    20 

Composition  of 94 

Compression  of 24 

Chopped 1 8,   22,  49 

Crew,  the 76 

Damp 26 

Dry 26 

Movement  of 28,  30 

Quantity  of 29 


172  SCIENCE    OF    THRESHING. 

PAGE 

Retarding    20 

Travel  of 26,  29,  30 

Wedging    21 

With  leaves    50 

STUFFING  BOXES 126 

SUGGESTION,  A 157,  158 

TABLES— 

Circles    159 

Explanation  of 101,    102 

Steam  . 98,  99,  100 

TAILINGS  ELEVATOR 33,  61 

TEMPERATURE 84 

TEETH— 

Concave n,  12,  20 

Cylinder    18 

Length  of 43 

Loose    1 8 

New    1 8 

Number  of 20 

Nuts 1 8,  19 

Space    43 

TESTING— 

Cylinder  Rings 147,    148 

Piston 147,  148 

Valves 147,  148 

THRESHING— 

Ancient  method 9,    n,    12 

Kinds  of  grain 9 

Process  of 9,  1 1,  23 


SCIENCE    OF    THRESHING.  173 

PAGE 

TRACTION  WHEELS — 

Diameter  of -.  .  137 

TOOL  Box- 
Importance   of 72 

VALVES — 

Description  of 128,  129,  130 

Keeping  True 125 

Lubrication  of    125 

Pressure  on 125 

Setting 134,    135 

Slide 124,  128 

WAGON  LOADER 42 

WASTING  GRAIN— 

Amount  of 7 8,  79 

Reasons  for 52,  53 

WATER— 

Changed  to  steam  by  heat 90 

Expansion  of  by  heat 85 

In  boiler 119 

WEATHER,  INFLUENCE  OF 47 

WEIGHERS    42 

WHEELS,  DRIVE   137 

WHEAT— 

Cleaning  weedy    62 

Spring 55 

WHISTLE— 

Code  of  Signals 138,  139 

How  to  sound 139 

Tone  of 139 

WIND  STACKER — 

Horse  power  required 40,  41,  42 


174  SCIENCE    OF    THRESHING. 

PAGE 

Speed  of ' 40,  41,  42 

Weight  of  air 40 

Weight  of  straw 41 

Finis. 


The  Parsons  and 
Ruth  Feeders 

A  Pair  That  Can't  be  Beat 


ALSO 

SUCCESS  ENGINE  TENDER 
SUCCESS  HUSKER  AND  SHREDDER 

BUFFALO    HAY    PRESS 
SUCCESS    FARM    AND    HAY    DERRICK 

SUCCESS    LIFTING   JACKS 
SUCCESSS  AUTOMATIC  BELT  GUIDE 

SUCCESS  STRAINER 
SUCCESS  CYLINDER  WRENCH 


Write  us  for  Catalogue  and  Prices 

Parsons  Band  Cutter 

and  Self  Feeder  Co. 


The  Gear/ess  Russell 


The;   Wind    Stacker 
that  has   reduced 


Threshing  to  a 

SCIENCE 


No  Gears 
No  Noise 
No   Vibration 
No  Choking 
Straight  Belt 
Takes  Least  Power 
The  Lightest  on 
Separation 
We  Guarantee  it. 


Attached  to  any  make  or 

size  of  Separator  at  Purchasers 

home  without  extra  cost. 


Russell  Wind  Stacker  Co. 

INDIANAPOLIS,  INDIANA. 


A  Large  Majority 

of  the  Most  Successful  Threshermen 
USE  SOLELY 

Gandy  Endless  Thresher  Belting 

The  Strongest  as  well  as  the  Most  Durable  Belt  Made.  Peer 
of  all  others  for  out-of-door  work.  Do  not  accept  imitations  as 
being  as  good.  They  positively  are  not.  We  brand  the  Gandy 
every  ten. feet,  "GENUINE  GANDY  BELT." 

SOLE  MANUFACTURERS 

The    Gandy    Belting    Company 

BALTIMORE,  MD.,  U.  S.  A. 


PRESERVO 

Waterproofs  Stack  and  Thresher  Covers 

Prevents  mildew  or  rotting  in  any  climate.  Will  not  crack, 
scale,  freeze  or  stick.  Old  covers  painted  with  PRESERVO 
are  made  as  good  as  new.  Endorsed  by  U.  S.  Government  and 
used  by  Barnum  &  Bailey  and  all  large  circus  people. 

Don't  throw  away  your  old  stack  covers — patch  them  and 
paint  them  with  PRESERVO.  It  will  make  them  better  than 
new  ones  without  it. 

Write  for  booklet  and    prices. 

W.  B.  ROBESON, 

MANUFACTURER, 

PORT  HURON,        -        MICHIGAN 


The  Famous  Sattley 
Attached  Stacker 


Is  the  SIMPLEST  Straw 

Stacker  Ever  Invented 

It  attaches  to  any  make  of  Separator 
and  is  the  most  successful  attached 
stacker  on  the  market. 


Manufactured 
by 


HEINEKE  &  CO. 

SPRINGFIELD,   ILLINOIS. 


THE  PORT  HURON  1905  RUSHER 

The  Malleable  Thresher 


The  Fort  Huron  Rusher  Separator  contains     59     Malleable     Castings,     not 
counting1    those    in    the    Feeder,    Bagger    and    Wind    Stacker. 

No  other  separator  equals  the  Port  Huron  in  strength  and  durability. 
Aside  from  the  large  number  of  malleable  castings,  the  Port  Huron  has 
great  strength  and  weight  in  its  hard  maple  frame,  thoroughly  supported 
by  iron  trusses,  straps  and  braces. 

The  Port  Huron  does  the  best  work  in  threshing  because  of  its  large 
well  proportioned  cylinder  (not  too  large)  and  its  large  amount  of  con- 
cave space. 

The  Port  Huron  does  the  best  work  in  separating  because  of  the 
large  adjustable  grate  with  fingers  through  which  the  grain  is  driven 
by  the  beater  just  after  it  leaves  the  cylinder. 

The  Port  Huron  has  plenty  of  separation  space  on  the  racks,  and  this 
space  is  made  effective  by  the  lifting  fingers,  which  thoroughly  toss  the 
straw  about  on  the  lower  rack,  and  the  undulations  and  fishbacks  which 
tear  the  straw  into  thin  sheets  on  the  upper  rack. 

The  Port  Huron  does  the  best  work  in  cleaning  because  of  its  side 
shake  shoe  and  adjustable  wind  guides  which  direct  the  blast  to  every 
part  of  the  sieves. 

LBLE    FEEDER 


Thirty-eight  or  about  two-thirds  of  the  castings  on  the  Port  Huron 
feeder  are  of  malleable  iron. 

The  distinctive  feature  of  the  Port  Huron  feeder  is  the  fact  that  it 
is  "bossed"  by  the  separator,  instead  of  bossing  the  separator.  It  does 
not  slug  or  choke  the  cylinder. 

THE  RUSHER  WIND  STACKER 

We  were  the  first  among  threshing  machinery  manufacturers  to  build 
wind  stackers.  The  Rusher  wind  stacker  is  the  result  of  many  years' 
experience  and  does  the  best  work. 

Write  Us  for  Most  Complete  Books  of  Specifications. 


PORT  HURON  ENGINE  &  THRESHER  CO., 


Southwestern-Fort  Huron  Co.,  St.  Louis,  Mo.;  Peoria,  111. 
Canadian   Fort   Huron   Company,   "Winnipeg,    Manitoba. 
Northwestern-Fort  Huron  Co.,  Minneapolis,  Minn.;  Fargo,  N.  D. 
Fort  Huron  Machinery  Co.,  Des  Moines.  Iowa. 
Wichita-Fort  Huron  Thresher  Co.,  Wichita,   Kansas. 
FOREIGN  TRADE  OFFICE,  11  Broadway,  New  York  City, 
Cable  Address,  "RUSHER." 


Reliable  Supplies 

MOST  COMPLETE  STOCK 

PROMPT  SHIPMENTS 

One  of  the  "Sciences  of  Threshing"  is  to  have  the  right 
kind  of  supplies  to  keep  the  machinery  going.  Don't  buy  stuff 
that  can  be  bought  cheaper  than  it  costs  to  produce  good  goods, 
but  buy  from  a  reliable  house,  one  that  stands  behind  its  goods. 


Our  Prices  are  Rig'Ht — Our  Goods 
are  Guaranteed. 


BELTING 

PACKING 

HOSE 

LACE  LEATHER 

TANK  PUMPS 

HEADLIGHTS 

INJECTORS 

STEAM  PUMPS 

SPROCKET  CHAIN 

BABBITT 


OIL 

GREASES 
LUBRICATORS 
OIL  PUMPS 
LIFTING  JACKS 
GOVERNORS 
WRENCHES 
BOILER  TOOLS 
VALVES 
SAWS,  ETC. 


Write  for  Supply  Catalogue 


M.  M.  Baker  &  Company 

PEORIA,  ILLINOIS 


Harrison  and  Water  Sts. 


Inside  Facts  for  Thinking  Threshermen 
ABOUT    THE    THEEE- WAY- CRANK  THRESHER. 

FACT  1 — It  has  steel  wheels  and  steel  axles. 

FACT   2 — It    has    our    "No-Shake,    No-Sag"    frame. 

FACT  3 — Wood   parts   are   made   from   well    seasoned   hard   maple,   white 

oak    and    yellow    poplar. 

the  front  bolster,  and  the  boxes  easily  adjusted. 

FACT  4 — The  cylinder  is  instantly  leveled  by  means  of  screw  jacks  under 
FACT   5 — It    is    quickly    set   and   the    screw    jacks    make    it    stand    "solid 

as   a   rock." 
FACT  6 — The  weight  of  the  main  drive  belt  is  carried  low  on  the  center 

of  the  front  axle,  so  that  the  frame  will  not  rack  from  the  dragging 

weight  of  belt  at  side  of  the  machine. 
FACT  7 — It  has  two  bearings  on  the  driving  end  of   the  cylinder  shaft, 

so  that  the  shaft  runs  smooth  and  cool,  and  can't  be  sprung  out  of 

line. 
FACT  8 — Its    construction   is    so   simple   and   all    parts    so   light   running 

that  only  three  belts  are  required.    (Some  others  have  five  to  ten  belts.) 
FACT   9 — The    cylinder   has    16    double    bars    with    large    outside   pulleys, 

that    give    steady,    strong    power    to    all    rear    parts    of    the    machine. 

This    30-inch    cylinder    knocks    all    the    grain    out    of    the    heads,    and 

about   90   per   cent   of  it   is   separated   on   the   long   stretch   of   grates 

before  reaching  the  racks. 
FACT  10 — Our  patent  Reversible  Tiger  Teeth  have  the  right  size,  weight 

and    shape    for    all    threshable    grains    and    seeds.       The    spring-lock 

washer   fastening   prevents   their   getting   loose,    and   they   can't    turn 

in  the  bars  and  don't  break.     Reversing  gives  you   the  equivalent  of 

a  new  set  of  teeth. 
FACT   11 — Our   patent   Concave   Adjuster   gives   the   easiest,   quickest   and 

most  perfect  adjustment  of  concaves  to  cylinder. 
FACT  12 — Every  part  of  the  thresher  is  in  perfect  line,  and  there  are  no 

hot    boxes    or    journals    to    contend    with;    nothing    on    which    straw 

could   wrap,    and   no  forks    or   pickers    to   give   trouble. 
FACT   13 — The   principle   of   separation   from    cylinder   to   weigher   is    the 

most  perfect  ever  devised.     The  up-hill  circular  motion  of  the  straw 

racks  does  the  work,  and  the  grain  goes  in  the  sack  instead  of  the 

straw   stack. 
FACT  14 — The  Three- Way-Crank  mechanism  is  so  perfectly  balanced  that 

it  has  no  dead  center,  and  gives  the  lightest  and  quietest  separating 

motion  you   ever  saw.     It  requires  no  adjusting  and  gives   twice  the 

throw  of  eccentric   devices. 
FACT  15 — It  has  a  larger  straw   space  above  the  racks   than   any   other 

thresher,   and   the  straw  moves  freely  without  bunching  or  carrying 

out  grain. 
FACT  16 — Our  patent   end-shake  chaffing  riddle   and   side-shake  shoe  and 

cleaning   riddle   prevent   wasting   on   the   riddles. 
FACT  17 — It  does  not  waste  grain  of  any  kind  in  any  condition  If  it  is 

properly  operated,  threshes  fastest,  cleans  best,  and  does  not  take  up 

the   thresherman's   profits   in   delays   or   cost    of   repairs. 
FACT  18 — It  is  the  result  of  seventy  years'  honest  effort  in  the  direction 

of  perfection,  and  is  several  steps  ahead  of  anybody's  else  best. 
Write  for  our  large  catalog  which  shows  all  the  "Stripes"  on  the  Tiger. 


GARR,  SCOTT  &  CO.,    - 


Richmond,  Indiana. 


The  New  Century 


With  gearless  and  noii 

blower  is  the  most  perfect 

and  most  profitable  Grain 

Separator  Saver  and  Cleaner 


Manufactured  solely  by  the 

Aultman  &  Taylor 

Machinery  Company 

Mansfield,         -          -          Ohio,  U.  S.  A. 


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Bowsher  Feed  Mills 


(Sold  with  or  without  elevator. ) 

Crush  ear  corn  (with  or  without  shucks}  and 
Grind  every  kind  of  small  grain.  Also  grind 
Kaffir-in-the-head.  Have  conical  shape  grind- 
ers Different  from  all  others  Can  run  empty 
without  injury. 

LIGHTEST  RUNNING 

Best  built,  most  convenient,  popular  with 
threshermen  everywhere.  Six  Sizes,  2  to  25 
horse  power.  Highest  awards  at  Chicago,  At- 
lanta, Omaha,  St.  Louis  World's  Fairs. 

B.  N,  P,  BOWSHER  CO, 


South  Bend, 


Indiana 


MACHINE. 
EXPERTS 

CLAIM 


The  Ideal  Adjustable  Sieve 


a  wonder.  Remember 
when  using1  an  Ideal 
Adjustable  Sieve,  you  can 

clean  all  kinds  of  grain 
and  seed  to  perfection.  It 
even  takes  out  all  dust 
and  fine  sediment,  and 
leaves  the  grain  perfectly 
clean.  The  lips  extend 
downward  at  an  angle  of 
about  45  degrees,  direct- 
ing the  blast  of  wind  up 
through  the  openings,  thus 
cleaning  the  grain  before 
it  strikes  the  Sieve.  The 
pitch  of  the  wind  blast  is 
never  changed  when  ad- 
justment is  made  for  dif- 
ferent kinds  of  grain.  One- 
third  lighter,  twice  as 
strong,  easy  to  place  in 
shoe  of  machine,  and  eas- 
ily adjusted.  When  order- 
ing new  machines  for  1906, 
be  sure  and  ask  for  the 
Ideal  Adjustable  Sieve. 

Write    at    once    for    cata- 
log   and    prices. 


THE  PLYMOUTH  MANF'G.  CO.,          Plymouth,  Ohio,  U.  S.  fl. 


WEIGHERS 


Hart   Grain  Weigher    Co. 

PEORIA,  ILL.,  U.  S.  A. 

Write  for  Catalogue. 


LOADERS 


In  Operation 


THE  "I.  X.  L." 

ROTARY  SEPARATING 

DEVICE 
SAVES 

ALL  THE   GRAIN 


The  "IXL"  is  the  only  attachment  of  its  kind  on  the  market. 
It  has  passed  the  experimental  stage.  Thousands  have  been 
sold. 

When  equipped  with  one  of  these  attachments  any  separator 
is  warranted  to  save  99  3-4  or  more  per  cent  of  the  threshed 
grain  from  the  straw.  We  know  it  will  do  this  and  after  making 
exhaustive  tests  we  find  that,  in  common  practice  today,  the 
average  separator  wastes  too  much  grain.  We  have  demon- 
strated that  what  we  claim  is  true  and  have  made  tests  in  a 
scientific  manner  and  the  results  of  these  tests  prove  that  we 
have  in  this  attachment  something  that  Saves  All  the  Grain. 

Write  today  for  full  information  and  pattern  showing  how 
the  "IXL"  is  attached  to  your  machine. 


CAN  BE 
ATTACHED 

TO  ANY 
SEPARATOR 


General   Location 


ADDRESS 


The  Sattley  Stacker  Co., 

DEP'T  "N,"  INDIANAPOLIS,  IND. 


THE  TRACTION  ENGINE 
CATECHISM 

This  is  the  name  of  a  new  book 

It  is  not  only  new  in  date  of  publication,  but  entirely  new 
in  form. 

You  probably  have  traction  engine  books  on  your  shelves. 
This  is  an  engine  book,  but  entirely  distinct. 

It  is  compiled  brom  the  "Questions  and  Answers"  depart- 
ment of  the  Threshermen's  Review. 

A  careful  selection  of  the  most  important  topics  has  been 
made,  and  the  various  subjects  are  so  carefully  classi- 
fied and  indexed  that  every  topic  is  easily  accessible. 

The  book  is  cloth  bound  in  the  standard  manner. 

Nearly  every  reader  of  uThe  Review"  is  regularly  reading 
our  "Questions  and  Answers"  and  knows  their  value 
to  the  engine  owner  and  engineer. 

This  book  is  by  far  the  best  reference  book  for  the  traction 
engineer  on  the  market. 

Size  and  style  same  as  "Science  of  Threshing." 

Price  per  copy,  $1.00. 
Published,  and  for  sale  by 

The  Threshermen's  Review 

St.  Joseph,  Michigan 


to  gas  engines. 


A  monthly  paper  of  84  to  100 
pages  given  entirely  to  the  sub- 
ject of  gasoline  engines  and 
accessories. 

This  is  one  of  the  greatest, 
growing,  power  questions  of 
the  day.  Gas  engines  are  per- 
forming wonders  and  bid  fair 
to  largely  revolutionize  the 
present  conditions.  Keep 
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Find  out  what  there  is  in  and 
It  may  mean  lots  to  you.  $1.00  per  year. 


PLAIN  GAS  ENGINE  SENSE 

One  hundred  and  twenty-four  pages 
of  good,  practical,  interesting  reading 
on  the  selection,  care,  operation  and 
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don't  have  to  know  about  them  to 
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you  want  and  ought  to  know.  Get 
it.  Read  it. 

5O  Cents  a  Copy. 

Address 

Gas  Power  Pub.  Qo 

St.  Joseph,  Michigan. 


